એરિસ્ટોટલ
પ્લેટો શિષ્ય, મહાન તત્ત્વજ્ઞાની, ભૌતિક વિજ્ઞાની, તત્ત્વમીમાંસાસક, કવિ, નાટ્યકાર, સંગીતકાર, તર્કશાસ્ત્રિ, મહાન વક્તા, રાજનીતિજ્ઞ, જીવવિજ્ઞાની, વનસ્પતિશાસ્ત્રિ, પ્રાણીશાસ્ત્રિ જેવી બહુમુખી પ્રતિભા ધરાવતા ગ્રિસના યુગપુરુષ, એરિસ્ટોટલ (ગ્રિક:  Aristotélēs) (ઇ.પૂ. ૩૮૪ – ઇ.પૂ. ૩૨૨) એલેક્ઝાન્ડર ના શીક્ષક હતા.

વિગત
તેમના ગુરુ પ્લેટો તથા સોક્રેટિસની સાથે જ એરિસ્ટોટલની ગણના પણ પાશ્ચાત્ય ફિલસૂફીના મહાનત્તમ વ્યક્તિઓ માં થાય છે.  તેઓ પાશ્ચાત્ય ફિલસૂફીની સર્વગ્રાહી પ્રણાલી, નીતિશાસ્ત્ર સૌંદર્ય શાસ્ત્ર, તર્કશાસ્ત્ર, વિજ્ઞાન, રાજનીતિ અને તાત્વિક મીમાંસાના ગ્રંથોના પ્રણેતા હતા. તેમના ભૌતિક વિજ્ઞાન વિશેના વિચારો નો પ્રભાવ મધ્યયુગીન વિચારધારા થી લઇ છેક નવજાગરણ સુધી રહ્યો. અંતતઃ આધુનિક ભૌતિક વિજ્ઞાન દ્વારા તેમના વિચારો બદલાવામાં આવ્યા. તેમની જૈવિક વિજ્ઞાન વિશેની કેટલીક ટિપ્પણીયો ને છેક  ઓગણીસમી સદીમા ખરી હોવાની પુષ્ટિ મળી. તેમનું તર્કશાસ્ત્ર વિશેનું અધ્યયન સૌથી પૌરાણિક માનવામા આવે છે. તેમના આ અધ્યયનોને ઓગણીસમી સદીના આધુનિક  પ્રમાણશાસ્ત્રમાં સમાવિષ્ટ કરવામાં આવ્યા. ઇસ્લામિક અને યહૂદી પરંપરાઓંની દાર્શનિક ઔર બ્રહ્મવૈજ્ઞાનિક વિચારધારા પર તેમનો ખુબ ઊંડો પ્રભાવ હતો. ઉપરાંત, મધ્યયુગમાં પણ તેમનો ખ્રિસ્તી ધર્મશાસ્ત્ર પર પ્રભાવ જાળવાયો જે ખાસ કરી ને "ઇસ્ટર્ન ઓર્થોડોક્સ" તથા "રોમન કેથોલિક ચર્ચ" પર જોવા મળે છે. આજે એરિસ્ટોટલ દર્શનના દરેક પાસાનો અભ્યાસ આધુનિક દર્શનશાસ્ત્રમાં થતો જોવા મળે છે. 
એરિસ્ટોટલ દ્વારા વિપુલ પ્રમાણમાં ગ્રંથોની રચના થયેલી છે (સીસરોએ તેમને "સોનાની એક નદી" રુપે આલેખ્યા હતા), પરંતુ હાલમાં ફક્ત એક તૃતિયાંશ  ભાગનું સાહિત્ય જાળવી શકાયું છે.

જીવન 

એરિસ્ટોટલ  ઈ.સ.પૂ.૩૮૪માં Stageira,Chalcidice,માં જન્મ્યા હતા,  , about 55 km east of modern-day Thessaloniki. His father, Nicomachus was the personal physician to King Amyntas of Macedon. એરિસ્ટોટલ was trained and educated as a member of the aristocracy. At about the age of eighteen, he went to એથેન્સ to continue his education at પ્લેટો's Academy. એરિસ્ટોટલ remained at the academy for nearly twenty years, not leaving until after પ્લેટો's death in 347 BC. He then traveled with Xenocrates to the court of his friend Hermias of Atarneus in એશીયા Minor. While in એશીયા, એરિસ્ટોટલ traveled with Theophrastus to the island of Lesbos, where together they researched the વનસ્પતિશાસ્ત્ર and પ્રાણીશાસ્ત્ર of the island. એરિસ્ટોટલ married Hermias's adoptive daughter (or niece) Pythias. She bore him a daughter, whom they named Pythias. Soon after Hermias' death, એરિસ્ટોટલ was invited by Philip of Macedon to become tutor to એલેક્ઝાન્ડર the Great in 343 B.C.

During his time as the head of Macedon's royal academy, એરિસ્ટોટલ gave lessons not only to એલેક્ઝાન્ડર, but also to two other future kings: Ptolemy and Cassander.  In his Politics, એરિસ્ટોટલ states that only one thing could justify monarchy, and that was if the virtue of the king and his family were greater than the virtue of the rest of the citizens put together. Tactfully, he included the young prince and his father in that category. એરિસ્ટોટલ encouraged એલેક્ઝાન્ડર toward eastern conquest, and his attitude towards Persia was unabashedly ethnocentric.  In one famous example, he counsels એલેક્ઝાન્ડર to be 'a leader to the Greeks and a despot to the barbarians, to look after the former as after friends and relatives, and to deal with the latter as with beasts or plants'. Near the end of એલેક્ઝાન્ડર's જીવન he began to suspect plots, and threatened એરિસ્ટોટલ in letters. એરિસ્ટોટલ had made no secret of his contempt for એલેક્ઝાન્ડર's pretense of divinity, and the king had executed એરિસ્ટોટલ's grand-nephew Callisthenes as a traitor. A widespread tradition in antiquity suspected એરિસ્ટોટલ of playing a role in એલેક્ઝાન્ડર's death, but there is little evidence for this.

By 335 BC he had returned to એથેન્સ, establishing his own school there known as the Lyceum. એરિસ્ટોટલ conducted courses at the school for the next twelve years. While in એથેન્સ, his wife Pythias died, and એરિસ્ટોટલ became involved with Herpyllis of Stageira, who bore him a son whom he named after his father, Nicomachus. According to the Suda, he also had an eromenos, Palaephatus of Abydus.

It is during this period in એથેન્સ from 335 B.C. to 323 B.C. when એરિસ્ટોટલ is believed to have composed many of his works. એરિસ્ટોટલ wrote many dialogues, only fragments of which survived. The works that have survived are in treatise form and were not, for the most part, intended for widespread publication, as they are generally thought to be lecture aids for his students. His most important treatises include Physics, Metaphysics, Nicomachean Ethics, Politics, De Anima (On the Soul) and Poetics. 

એરિસ્ટોટલ not only studied almost every subject possible at the time, but made significant contributions to most of them. In physical science, એરિસ્ટોટલ studied anatomy, astronomy, અર્થશાસ્ત્ર, embryology, geography, geology, meteorology, ભૌતિક વિજ્ઞાન and પ્રાણીશાસ્ત્ર. In philosophy, he wrote on aesthetics, ethics, government, તત્ત્વમીમાંસા, રાજનીતિ, psychology, rhetoric and theology. He also studied education, foreign customs, literature and poetry. His combined works constitute a virtual encyclopedia of Greek knowledge. It has been suggested that એરિસ્ટોટલ was probably the last person to know everything there was to be known in his own time.

Upon એલેક્ઝાન્ડર's death, anti-Macedonian sentiment in એથેન્સ once again flared. Eurymedon the hierophant denounced એરિસ્ટોટલ for not holding the gods in honor. એરિસ્ટોટલ fled the city to his mother's family estate in Chalcis, explaining, "I will not allow the Athenians to sin twice against philosophy," a reference to એથેન્સ's prior trial and execution of સોક્રેટિસ. However, he died in Euboea of natural causes within the year (in 322 BC). એરિસ્ટોટલ named chief executor his student Antipater and left a will in which he asked to be buried next to his wife.

તર્કશાસ્ત્ર 

એરિસ્ટોટલ's conception of તર્કશાસ્ત્ર was the dominant form of તર્કશાસ્ત્ર until 19th century advances in mathematical તર્કશાસ્ત્ર. Kant stated in the Critique of Pure Reason that એરિસ્ટોટલ's theory of તર્કશાસ્ત્ર completely accounted for the core of deductive inference.

ઇતીહાસ 
એરિસ્ટોટલ "says that 'on the subject of reasoning' he 'had nothing else on an earlier date to speak of'". However, પ્લેટો reports that syntax was devised before him, by Prodikos of Keos, who was concerned by the correct use of words. Logic seems to have emerged from dialectics; the earlier philosophers made frequent use of concepts like reductio ad absurdum in their discussions, but never truly understood the logical implications. Even પ્લેટો had difficulties with તર્કશાસ્ત્ર; although he had a reasonable conception of a deduction system, he could never actually construct one and relied instead on his dialectic. પ્લેટો believed that deduction would simply follow from premises, hence he focused on maintaining solid premises so that the conclusion would logically follow. Consequently, પ્લેટો realized that a method for obtaining conclusions would be most beneficial. He never succeeded in devising such a method, but his best attempt was published in his book Sophist, where he introduced his division method.

તર્કશૈલી' 

What we today call Aristotelian તર્કશાસ્ત્ર, એરિસ્ટોટલ himself would have labeled "analytics". The term "logic" he reserved to mean dialectics. Most of એરિસ્ટોટલ 's work is probably not in its original form, since it was most likely edited by students and later lecturers. The logical works of એરિસ્ટોટલ were compiled into six books in about the early 1st century AD:
 Categories
 On Interpretation
 Prior Analytics
 Posterior Analytics
 Topics
 On Sophistical Refutations

The order of the books (or the teachings from which they are composed) is not certain, but this list was derived from analysis of એરિસ્ટોટલ's writings. It goes from the basics, the analysis of simple terms in the Categories, to the study of more complex forms, namely, syllogisms (in the Analytics) and dialectics (in the Topics and Sophistical Refutations). There is one volume of એરિસ્ટોટલ's concerning logic not found in the Organon, namely the fourth book of Metaphysics..

વૈજ્ઞાનીક પદ્ધતી 

Like his teacher પ્લેટો, એરિસ્ટોટલ's philosophy aims at the universal. એરિસ્ટોટલ, however, found the universal in particular things, which he called the essence of things, while પ્લેટો finds that the universal exists apart from particular things, and is related to them as their prototype or exemplar. For એરિસ્ટોટલ, therefore, philosophic method implies the ascent from the study of particular phenomena to the knowledge of essences, while for પ્લેટો philosophic method means the descent from a knowledge of universal Forms (or ideas) to a contemplation of particular imitations of these. For એરિસ્ટોટલ, "form" still refers to the unconditional basis of phenomena but is "instantiated" in a particular substance (see Universals and particulars, below). In a certain sense, એરિસ્ટોટલ's method is both inductive and deductive, while પ્લેટો's is essentially deductive from a priori principles.

In એરિસ્ટોટલ's terminology, "natural philosophy" is a branch of philosophy examining the phenomena of the natural world, and included fields that would be regarded today as ભૌતિક વિજ્ઞાન, biology and other natural sciences. In modern times, the scope of philosophy has become limited to more generic or abstract inquiries, such as ethics and તત્ત્વમીમાંસા, in which logic plays a major role. Today's philosophy tends to exclude empirical study of the natural world by means of the scientific method. In contrast, એરિસ્ટોટલ's philosophical endeavors encompassed virtually all facets of intellectual inquiry.

In the larger sense of the word, એરિસ્ટોટલ makes philosophy coextensive with reasoning, which he also would describe as "વિજ્ઞાન". Note, however, that his use of the term વિજ્ઞાન carries a different meaning than that covered by the term "scientific method". For એરિસ્ટોટલ, "all વિજ્ઞાન(dianoia) is either practical, poetical or theoretical" (Metaphysics 1025b25). By practical વિજ્ઞાન, he means ethics and રાજનીતિ; by poetical વિજ્ઞાન, he means the study of poetry and the other fine arts; by theoretical વિજ્ઞાન, he means ભૌતિક વિજ્ઞાન, mathematics and તત્ત્વમીમાંસા.

If logic (or "analytics") is regarded as a study preliminary to philosophy, the divisions of Aristotelian philosophy would consist of: (1) Logic; (2) Theoretical Philosophy, including Metaphysics, Physics, Mathematics, (3) Practical Philosophy and (4) Poetical Philosophy.

In the period between his two stays in એથેન્સ, between his times at the Academy and the Lyceum, એરિસ્ટોટલ conducted most of the scientific thinking and research for which he is renowned today. In fact, most of એરિસ્ટોટલ's જીવન was devoted to the study of the objects of natural science. એરિસ્ટોટલ's તત્ત્વમીમાંસા contains observations on the nature of numbers but he made no original contributions to mathematics. He did, however, perform original research in the natural sciences, દા.ત., વનસ્પતિશાસ્ત્ર, પ્રાણીશાસ્ત્ર, ભૌતિક વિજ્ઞાન, astronomy, chemistry, meteorology, and several other sciences.

એરિસ્ટોટલ's writings on વિજ્ઞાન are largely qualitative, as opposed to quantitative. Beginning in the sixteenth century, scientists began applying mathematics to the physical sciences, and એરિસ્ટોટલ's work in this area was deemed hopelessly inadequate. His failings were largely due to the absence of concepts like mass, velocity, force and temperature. He had a conception of speed and temperature, but no quantitative understanding of them, which was partly due to the absence of basic experimental devices, like clocks and thermometers.

His writings provide an account of many scientific observations, a mixture of precocious accuracy and curious errors. દા.ત., in his History of Animals he claimed that human males have more teeth than females. In a similar vein, John Philoponus, and later Galileo, showed by simple experiments that એરિસ્ટોટલ's theory that a heavier object falls faster than a lighter object is incorrect. On the other hand, એરિસ્ટોટલrefuted Democritus's claim that the Milky Way was made up of "those stars which are shaded by the earth from the sun's rays," pointing out (correctly, even if such reasoning was bound to be dismissed for a long time) that, given "current astronomical demonstrations" that "the size of the sun is greater than that of the earth and the distance of the stars from the earth many times greater than that of the sun, then...the sun shines on all the stars and the earth screens none of them."

In places, એરિસ્ટોટલ goes too far in deriving 'laws of the universe' from simple observation and over-stretched reason. Today's scientific method assumes that such thinking without sufficient facts is ineffective, and that discerning the validity of one's hypothesis requires far more rigorous experimentation than that which એરિસ્ટોટલ used to support his laws.

એરિસ્ટોટલ also had some scientific blind spots. He posited a geocentric cosmology that we may discern in selections of the Metaphysics, which was widely accepted up until the 1500s. From the 3rd century to the 1500s, the dominant view held that the પૃથ્વી was the center of the universe (geocentrism).

Since he was perhaps the philosopher most respected by European thinkers during and after the Renaissance, these thinkers often took એરિસ્ટોટલ's erroneous positions as given, which held back વિજ્ઞાન in this epoch. However, એરિસ્ટોટલ's scientific shortcomings should not mislead one into forgetting his great advances in the many scientific fields. For instance, he founded logic as a formal વિજ્ઞાન and created foundations to biology that were not superseded for two millennia. Moreover, he introduced the fundamental notion that nature is composed of things that change and that studying such changes can provide useful knowledge of underlying constants.

ભૌતિક વિજ્ઞાન

પંચ મહાભૂત 

 અગ્નિ, which is hot and dry.
 પૃથ્વી, which is cold and dry.
 વાયુ , which is hot and wet.
 જળ, which is cold and wet.
 Aether, which is the divine substance that makes up the heavenly spheres and heavenly bodies (stars and planets).

Each of the four earthly elements has its natural place; the earth at the centre of the universe, then જળ, then વાયુ, then અગ્નિ. When they are out of their natural place they have natural motion, requiring no external cause, which is towards that place; so bodies sink in જળ, air bubbles up, rain falls, flame rises in air. The heavenly element has perpetual circular motion.

Causality, The Four Causes

 The material cause is that from which a thing comes into existence as from its part, constituents, substratum or materials. This reduces the explanation of causes to the parts (factors, elements, constituents, ingredients) forming the whole (system, structure, compound, complex, composite, or combination), a relationship known as the part-whole causation. Simply put it is the influence of the material substances on the event. So imagine two dominos, the first of which is lighter. The first is knocked over into the second but does not have enough power to knock it over, this is Material cause.
 The formal cause tells us what a thing is, that any thing is determined by the definition, form, pattern, essence, whole, synthesis or archetype. It embraces the account of causes in terms of fundamental principles or general laws, as the whole (i.e., macrostructure) is the cause of its parts, a relationship known as the whole-part causation. Plainly put it is the influence of the form (essence) of the things on the event. So take the two dominos again except this time the second is shaped to prevent it from falling *eg. triangular.* this is formal cause.
 The efficient cause is that from which the change or the ending of the change first starts. It identifies 'what makes of what is made and what causes change of what is changed' and so suggests all sorts of agents, nonliving or living, acting as the sources of change or movement or rest. Representing the current understanding of causality as the relation of cause and effect, this covers the modern definitions of "cause" as either the agent or agency or particular events or states of affairs. More simply again that which immediately sets the thing in motion. So take the two dominos this time of equal weighting, the first is knocked over causing the second also to fall over. This is effectively efficient cause.
 The final cause is that for the sake of which a thing exists or is done, including both purposeful and instrumental actions and activities. The final cause or telos is the purpose or end that something is supposed to serve, or it is that from which and that to which the change is. This also covers modern ideas of mental causation involving such psychological causes as volition, need, motivation, or motives, rational, irrational, ethical, all that gives purpose to behavior.
Additionally, things can be causes of one another, causing each other reciprocally, as hard work causes fitness and vice versa, although not in the same way or function, the one is as the beginning of change, the other as the goal. (Thus એરિસ્ટોટલ first suggested a reciprocal or circular causality as a relation of mutual dependence or influence of cause upon effect). Moreover, એરિસ્ટોટલ indicated that the same thing can be the cause of contrary effects; its presence and absence may result in different outcomes. Simply it is the goal or purpose that brings about an event (not necessarily a mental goal). Taking our two dominos, it requires someone to intentionally knock the dominos over as they cannot fall themselves.

એરિસ્ટોટલ marked two modes of causation: proper (prior) causation and accidental (chance) causation. All causes, proper and incidental, can be spoken as potential or as actual, particular or generic. The same ભાષા refers to the effects of causes, so that generic effects assigned to generic causes, particular effects to particular causes, operating causes to actual effects. Essentially, causality does not suggest a temporal relation between the cause and the effect.

All further investigations of causality will consist of imposing the favorite hierarchies on the order causes, such as final > efficient > material > formal (Thomas Aquinas), or of restricting all causality to the material and efficient causes or to the efficient causality (deterministic or chance) or just to regular sequences and correlations of natural phenomena (the natural sciences describing how things happen instead of explaining the whys and wherefores).

તકો અને સ્વયંસ્ફૂરણા 
Spontaneity and chance are causes of effects. Chance as an incidental cause lies in the realm of accidental things. It is "from what is spontaneous" (but note that what is spontaneous does not come from chance). For a better understanding of એરિસ્ટોટલ's conception of "chance" it might be better to think of "coincidence": Something takes place by chance if a person sets out with the intent of having one thing take place, but with the result of another thing (not intended) taking place. દા.ત.: A person seeks donations. That person may find another person willing to donate a substantial sum. However, if the person seeking the donations met the person donating, not for the purpose of collecting donations, but for some other purpose, એરિસ્ટોટલ would call the collecting of the donation by that particular donator a result of chance. It must be unusual that something happens by chance. In other words, if something happens all or most of the time, we cannot say that it is by chance.

There is also more specific kind of chance, which એરિસ્ટોટલ names "luck", that can only apply to human beings, since it is in the sphere of moral actions. According to એરિસ્ટોટલ, luck must involve choice (and thus deliberation), and only humans are capable of deliberation and choice. "What is not capable of action cannot do anything by chance".

તાત્વિક મીમાંસા 

એરિસ્ટોટલ defines તત્ત્વમીમાંસા as "the knowledge of immaterial being," or of "being in the highest degree of abstraction." He refers to તત્ત્વમીમાંસા as "first philosophy", as well as "the theologic science."

તત્ત્વ, સંભાવ્યતા અને યથાર્થતા 
એરિસ્ટોટલ examines the concept of substance and essence (ousia) in his Metaphysics, Book VII and he concludes that a particular substance is a combination of both matter and form. As he proceeds to the book VIII, he concludes that the matter of the substance is the substratum or the stuff of which it is composed, e.g. the matter of the house are the bricks, stones, timbers etc., or whatever constitutes the potential house. While the form of the substance, is the actual house, namely 'covering for bodies and chattels' or any other differentia (see also predicables). The formula that gives the components is the account of the matter, and the formula that gives the differentia is the account of the form.

With regard to the change (kinesis) and its causes now, as he defines in his Physics and On Generation and Corruption 319b-320a, he distinguishes the coming to be from: 1) growth and diminution, which is change in quantity; 2) locomotion, which is change in space; and 3) alteration, which is change in quality.

The coming to be is a change where nothing persists of which the resultant is a property. In that particular change he introduces the concept of potentiality (dynamis) and actuality (entelecheia) in association with the matter and the form.

Referring to potentiality, this is what a thing is capable of doing, or being acted upon, if it is not prevented by something else. દા.ત., the seed of a plant in the soil is potentially (dynamei) plant, and if is not prevented by something, it will become a plant. Potentially beings can either 'act' (poiein) or 'be acted upon' (paschein), which can be either innate or learned. દા.ત., the eyes possess the potentiality of sight (innate - being acted upon), while the capability of playing the flute can be possessed by learning (exercise - acting).

Actuality is the fulfillment of the end of the potentiality. Because the end (telos) is the principle of every change, and for the sake of the end exists potentiality, therefore actuality is the end. Referring then to our previous example, we could say that actuality is when the seed of the plant becomes a plant.

" For that for the sake of which a thing is, is its principle, and the becoming is for the sake of the end; and the actuality is the end, and it is for the sake of this that the potentiality is acquired. For animals do not see in order that they may have sight, but they have sight that they may see."

In conclusion, the matter of the house is its potentiality and the form is its actuality. The formal cause (aitia) then of that change from potential to actual house, is the reason (logos) of the house builder and the final cause is the end, namely the house itself. Then એરિસ્ટોટલ proceeds and concludes that the actuality is prior to potentiality in formula, in time and in substantiality.

With this definition of the particular substance (i.e., matter and form), એરિસ્ટોટલ tries to solve the problem of the unity of the beings, e.g., what is that makes the man one? Since, according to પ્લેટો there are two Ideas: animal and biped, how then is man a unity? However, according to એરિસ્ટોટલ, the potential being (matter) and the actual one (form) are one and the same thing.

સાર્વત્રિક અને વિશેષત: 

એરિસ્ટોટલ's predecessor, પ્લેટો, argued that all things have a universal form, which could be either a property, or a relation to other things. When we look at an apple, દા.ત., we see an apple, and we can also analyze a form of an apple. In this distinction, there is a particular apple and a universal form of an apple. Moreover, we can place an apple next to a book, so that we can speak of both the book and apple as being next to each other.

પ્લેટો argued that there are some universal forms that are not a part of particular things. દા.ત., it is possible that there is no particular good in existence, but "good" is still a proper universal form. Bertrand Russell is a contemporary philosopher that agreed with પ્લેટો on the existence of "uninstantiated universals".

એરિસ્ટોટલ disagreed with પ્લેટો on this point, arguing that all universals are instantiated. એરિસ્ટોટલ argued that there are no universals that are unattached to existing things. According to એરિસ્ટોટલ, if a universal exists, either as a particular or a relation, then there must have been, must be currently, or must be in the future, something on which the universal can be predicated. Consequently, according to એરિસ્ટોટલ, if it is not the case that some universal can be predicated to an object that exists at some period of time, then it does not exist.

One way for contemporary philosophers to justify this position is by asserting the eleatic principle.

In addition, એરિસ્ટોટલdisagreed with પ્લેટો about the location of universals. As પ્લેટો spoke of the world of the forms, a location where all universal forms subsist, એરિસ્ટોટલ maintained that universals exist within each thing on which each universal is predicated. So, according to એરિસ્ટોટલ, the form of apple exists within each apple, rather than in the world of the forms.

જીવવિજ્ઞાન અને વૈદીક 
In Aristotelian વિજ્ઞાન, most especially in biology, things he saw himself have stood the test of time better than his retelling of the reports of others, which contain error and superstition. He dissected animals, but not humans and his ideas on how the human body works have been almost entirely superseded.

પ્રયોગમૂલક સંશોધન 

એરિસ્ટોટલ is the earliest natural historian whose work has survived in some detail. એરિસ્ટોટલ certainly did research on the natural ઇતીહાસ of Lesbos, and the surrounding seas and neighbouring areas. The works that reflect this research, such as History of Animals, Generation of Animals, and Parts of Animals, contain some observations and interpretations, along with sundry myths and mistakes. The most striking passages are about the sea-life visible from observation on Lesbos and available from the catches of fishermen. His observations on catfish, electric fish (Torpedo) and angler-fish are detailed, as is his writing on cephalopods, namely, Octopus, Sepia (cuttlefish) and the paper nautilus (Argonauta argo). His description of the hectocotyl arm was about two thousand years ahead of its time, and widely disbelieved until its rediscovery in the ઓગણીસમી સદી. He separated the aquatic mammals from fish, and knew that sharks and rays were part of the group he called Selachē (selachians).

Another good example of his methods comes from the Generation of Animals in which એરિસ્ટોટલ describes breaking open fertilized chicken eggs at intervals to observe when visible organs were generated.

He gave accurate descriptions of ruminants' four-chambered fore-stomachs, and of the ovoviviparous embryological development of the hound shark Mustelus mustelus.

જીવોનું વર્ગીકરણ 
એરિસ્ટોટલ's classification of living things contains some elements which still existed in the ઓગણીસમી સદી. What the modern zoologist would call vertebrates and invertebrates, એરિસ્ટોટલ called 'animals with blood' and 'animals without blood' (he was not to know that complex invertebrates do make use of haemoglobin, but of a different kind from vertebrates). Animals with blood were divided into live-bearing (humans and mammals), and egg-bearing (birds and fish). Invertebrates ('animals without blood') are insects, crustacea (divided into non-shelled – cephalopods – and shelled) and testacea (molluscs). In some respects, this incomplete classification is better than that of Linnaeus, who crowded the invertebrata together into two groups, Insecta and Vermes (worms).

For Charles Singer, "Nothing is more remarkable than [એરિસ્ટોટલ's] efforts to [exhibit] the relationships of living things as a scala naturae" એરિસ્ટોટલ's History of Animals classified organisms in relation to a hierarchical "Ladder of Life" (scala naturae), placing them according to complexity of structure and function so that higher organisms showed greater vitality and ability to move.

એરિસ્ટોટલ believed that intellectual purposes, i.e., formal causes, guided all natural processes. Such a teleological view gave એરિસ્ટોટલ cause to justify his observed data as an expression of formal design. Noting that "no animal has, at the same time, both tusks and horns," and "a single-hooved animal with two horns I have never seen," એરિસ્ટોટલ suggested that Nature, giving no animal both horns and tusks, was staving off vanity, and giving creatures faculties only to such a degree as they are necessary. Noting that ruminants had a multiple stomachs and weak teeth, he supposed the first was to compensate for the latter, with Nature trying to preserve a type of balance.

In a similar fashion, એરિસ્ટોટલ believed that creatures were arranged in a graded scale of perfection rising from plants on up to man, the scala naturae or Great Chain of Being. His system had eleven grades, arranged according "to the degree to which they are infected with potentiality", expressed in their form at birth. The highest animals laid warm and wet creatures alive, the lowest bore theirs cold, dry, and in thick eggs.

જીવવિજ્ઞાન વિષયક સિદ્ધાન્ત 
એરિસ્ટોટલ also held that the level of a creature's perfection was reflected in its form, but not preordained by that form. Ideas like this, and his ideas about souls, are not regarded as વિજ્ઞાન at all in modern times.

He placed emphasis on the type(s) of soul an organism possessed, asserting that plants possess a vegetative soul, responsible for reproduction and growth, animals a vegetative and a sensitive soul, responsible for mobility and sensation, and humans a vegetative, a sensitive, and a rational soul, capable of thought and reflection.

એરિસ્ટોટલ, in contrast to earlier philosophers, but in accordance with the Egyptians, placed the rational soul in the heart, rather than the brain. Notable is એરિસ્ટોટલ's division of sensation and thought, which generally went against previous philosophers, with the exception of Alcmaeon.

His analysis of procreation is frequently criticized on the grounds that it presupposes an active, ensouling masculine element bringing જીવન to an inert, passive, lumpen female element; it is on these grounds that એરિસ્ટોટલ is considered by some feminist critics to have been a misogynist.

એરિસ્ટોટલનો શીષ્ય, થીઓફરેટસ 

એરિસ્ટોટલ's successor at the Lyceum, Theophrastus, wrote a series of books on વનસ્પતિશાસ્ત્ર—the History of Plants—which survived as the most important contribution of antiquity to વનસ્પતિશાસ્ત્ર, even into the Middle Ages. Many of Theophrastus' names survive into modern times, such as carpos for fruit, and pericarpion for seed vessel.

Rather than focus on formal causes, as એરિસ્ટોટલ did, Theophrastus suggested a mechanistic scheme, drawing analogies between natural and artificial processes, and relying on એરિસ્ટોટલ's concept of the efficient cause. Theophrastus also recognized the role of sex in the reproduction of some higher plants, though this last discovery was lost in later ages.

ગ્રીસના વૈદકશાસ્ત્ર પર પ્રભાવ (Hellenistic medicine) 

After Theophrastus, the Lyceum failed to produce any original work. Though interest in એરિસ્ટોટલ's ideas survived, they were generally taken unquestioningly. It is not until the age of Alexandria under the Ptolemies that advances in biology can be again found.

The first medical teacher at Alexandria Herophilus of Chalcedon, corrected એરિસ્ટોટલ, placing intelligence in the brain, and connected the nervous system to motion and sensation. Herophilus also distinguished between veins and arteries, noting that the latter pulse while the former do not. Though a few ancient atomists such as Lucretius challenged the teleological viewpoint of Aristotelian ideas about જીવન, teleology (and after the rise of Christianity, natural theology) would remain central to biological thought essentially until the 18th and 19th centuries. Ernst Mayr claimed that there was "nothing of any real consequence in biology after Lucretius and Galen until the Renaissance." એરિસ્ટોટલ's ideas of natural ઇતીહાસ and medicine survived, but they were generally taken unquestioningly.

વ્યાવહારિક દર્શન

નીતિશાસ્ત્ર 

એરિસ્ટોટલ considered ethics to be a practical વિજ્ઞાન, i.e., one mastered by doing rather than merely reasoning. Further, એરિસ્ટોટલ believed that ethical knowledge is not certain knowledge (such as તત્ત્વમીમાંસા or epistemology) but is general knowledge. He wrote several treatises on ethics, including most notably, Nichomachean Ethics, in which he outlines what is commonly called virtue ethics.

એરિસ્ટોટલ taught that virtue has to do with the proper function of a thing. An eye is only a good eye in so much as it can see, because the proper function of an eye is sight. એરિસ્ટોટલ reasoned that man must have a function uncommon to anything else, and that this function must be an activity of the soul. એરિસ્ટોટલ identified the best activity of the soul as eudaimonia: a happiness or joy that pervades the good જીવન. એરિસ્ટોટલ taught that to achieve the good જીવન, one must live a balanced જીવન and avoid excess. This balance, he taught, varies among different persons and situations, and exists as a golden mean between two vices - one an excess and one a deficiency.

રાજ્યનીતિ 

In addition to his works on ethics, which address the individual, એરિસ્ટોટલ addressed the city in his work titled Politics. એરિસ્ટોટલ's conception of the city is organic, and he is considered one of the first to conceive of the city in this manner. એરિસ્ટોટલ considered the city to be a natural community. Moreover, he considered the city to be prior to the family which in turn is prior to the individual, i.e., last in the order of becoming, but first in the order of being . He is also famous for his statement that "man is by nature a political animal." એરિસ્ટોટલ conceived of રાજનીતિ as being like an organism rather than like a machine, and as a collection of parts none of which can exist without the others.

It should be noted that the modern understanding of a political community is that of the state. However, the state was foreign to એરિસ્ટોટલ. He referred to political communities as cities. એરિસ્ટોટલ understood a city as a political "partnership"  and not one of a social contract (or compact) or a political community as understood by Niccolò Machiavelli. Subsequently, a city is created not to avoid injustice or for economic stability , but rather to live a good જીવન: "The political partnership must be regarded, therefore, as being for the sake of noble actions, not for the sake of living together" . This can be distinguished from the social contract theory which individuals leave the state of nature because of "fear of violent death" or its "inconveniences."

વકતૃત્વ અને કાવ્ય 

એરિસ્ટોટલ considered epic poetry, tragedy, comedy, dithyrambic poetry and music to be imitative, each varying in imitation by media, object, and manner. દા.ત., music imitates with the media of rhythm and harmony, whereas dance imitates with rhythm alone, and poetry with ભાષા. The forms also differ in their object of imitation. Comedy, for instance, is a dramatic imitation of men worse than average; whereas tragedy imitates men slightly better than average. Lastly, the forms differ in their manner of imitation - through narrative or character, through change or no change, and through drama or no drama. એરિસ્ટોટલbelieved that imitation is natural to mankind and constitutes one of mankind's advantages over animals.

While it is believed that એરિસ્ટોટલ's Poetics comprised two books - one on comedy and one on tragedy - only the portion that focuses on tragedy has survived. એરિસ્ટોટલ taught that tragedy is composed of six elements: plot-structure, character, style, spectacle, and lyric poetry. The characters in a tragedy are merely a means of driving the story; and the plot, not the characters, is the chief focus of tragedy. Tragedy is the imitation of action arousing pity and fear, and is meant to effect the catharsis of those same emotions. એરિસ્ટોટલ concludes Poetics with a discussion on which, if either, is superior: epic or tragic mimesis. He suggests that because tragedy possesses all the attributes of an epic, possibly possesses additional attributes such as spectacle and music, is more unified, and achieves the aim of its mimesis in shorter scope, it can be considered superior to epic.

એરિસ્ટોટલ was a keen systematic collector of riddles, folklore, and proverbs; he and his school had a special interest in the riddles of the Delphic Oracle and studied the fables of Aesop.

લુપ્ત ગ્રંથો 
According to a distinction that originates with એરિસ્ટોટલ himself, his writings are divisible into two groups: the "exoteric" and the "esoteric". Most scholars have understood this as a distinction between works એરિસ્ટોટલintended for the public (exoteric), and the more technical works (esoteric) intended for the narrower audience of એરિસ્ટોટલ's students and other philosophers who were familiar with the jargon and issues typical of the Platonic and Aristotelian schools. Another common assumption is that none of the exoteric works is extant - that all of એરિસ્ટોટલ's extant writings are of the esoteric kind. Current knowledge of what exactly the exoteric writings were like is scant and dubious, though many of them may have been in dialogue form. (Fragments of some of એરિસ્ટોટલ's dialogues have survived.) Perhaps it is to these that Cicero refers when he characterized એરિસ્ટોટલ's writing style as "a river of gold"; it is hard for many modern readers to accept that one could seriously so admire the style of those works currently available to us. However, some modern scholars have warned that we cannot know for certain that Cicero's praise was reserved specifically for the exoteric works; a few modern scholars have actually admired the concise writing style found in એરિસ્ટોટલ's extant works.

One major question in the ઇતીહાસ of એરિસ્ટોટલ's works, then, is how were the exoteric writings all lost, and how did the ones we now possess come to us? The story of the original manuscripts of the esoteric treatises is described by Strabo in his Geography and Plutarch in his Parallel Lives. The manuscripts were left from એરિસ્ટોટલto his successor Theophrastus, who in turn willed them to Neleus of Scepsis. Neleus supposedly took the writings from એથેન્સ to Scepsis, where his heirs let them languish in a cellar until the first century BC, when Apellicon of Teos discovered and purchased the manuscripts, bringing them back to એથેન્સ. According to the story, Apellicon tried to repair some of the damage that was done during the manuscripts' stay in the basement, introducing a number of errors into the text. When Lucius Cornelius Sulla occupied એથેન્સ in 86 BC, he carried off the library of Apellicon to Rome, where they were first published in 60 BC by the grammarian Tyrannion of Amisus and then by philosopher Andronicus of Rhodes.

Carnes Lord attributes the popular belief in this story to the fact that it provides "the most plausible explanation for the rapid eclipse of the Peripatetic school after the middle of the third century, and for the absence of widespread knowledge of the specialized treatises of એરિસ્ટોટલ throughout the Hellenistic period, as well as for the sudden reappearance of a flourishing Aristotelianism during the first century B.C." Lord voices a number of reservations concerning this story, however. First, the condition of the texts is far too good for them to have suffered considerable damage followed by Apellicon's inexpert attempt at repair. Second, there is "incontrovertible evidence," Lord says, that the treatises were in circulation during the time in which Strabo and Plutarch suggest they were confined within the cellar in Scepsis. Third, the definitive edition of એરિસ્ટોટલ 's texts seems to have been made in એથેન્સ some fifty years before Andronicus supposedly compiled his. And fourth, ancient library catalogues predating Andronicus' intervention list an Aristotelean corpus quite similar to the one we currently possess. Lord sees a number of post-Aristotelean interpolations in the Politics, દા.ત., but is generally confident that the work has come down to us relatively intact.

As the influence of the falsafa grew in the West, in part due to Gerard of Cremona's translations and the spread of Averroism, the demand for એરિસ્ટોટલ's works grew. William of Moerbeke translated a number of them into Latin. When Thomas Aquinas wrote his theology, working from Moerbeke's translations, the demand for એરિસ્ટોટલ's writings grew and the Greek manuscripts returned to the West, stimulating a revival of Aristotelianism in Europe, and ultimately revitalizing European thought through Muslim influence in Spain to fan the embers of the Renaissance.

પૂર્વગામી 

Twenty-three hundred years after his death, એરિસ્ટોટલremains one of the most influential people who ever lived. He was the founder of formal logic, pioneered the study of પ્રાણીશાસ્ત્ર, and left every future scientist and philosopher in his debt through his contributions to the scientific method. Despite these accolades, many of એરિસ્ટોટલ's errors held back વિજ્ઞાન considerably. Bertrand Russell notes that "almost every serious intellectual advance has had to begin with an attack on some Aristotelian doctrine". Russell also refers to એરિસ્ટોટલ's ethics as "repulsive", and calls his logic  "as definitely antiquated as Ptolemaic astronomy". Russell notes that these errors make it difficult to do historical justice to એરિસ્ટોટલ, until one remembers how large of an advance he made upon all of his predecessors.

The immediate influence of એરિસ્ટોટલ's work was felt as the Lyceum grew into the Peripatetic school. એરિસ્ટોટલ's notable students included Aristoxenus, Dicaearchus, Demetrius of Phalerum, Eudemos of Rhodes, Harpalus, Hephaestion, Meno, Mnason of Phocis, Nicomachus, and Theophrastus. એરિસ્ટોટલ's influence over એલેક્ઝાન્ડર the Great is seen in the latter's bringing with him on his expedition a host of zoologists, botanists, and researchers. He had also learned a great deal about Persian customs and traditions from his teacher. Although his respect for એરિસ્ટોટલwas diminished as his travels made it clear that much of એરિસ્ટોટલ's geography was clearly wrong, when the old philosopher released his works to the public, એલેક્ઝાન્ડર complained "Thou hast not done well to publish thy acroamatic doctrines; for in what shall I surpass other men if those doctrines wherein I have been trained are to be all men's common property?"

એરિસ્ટોટલ is referred to as "The Philosopher" by Scholastic thinkers such as Thomas Aquinas. See Summa Theologica, Part I, Question 3, etc. These thinkers blended Aristotelian philosophy with Christianity, bringing the thought of Ancient Greece into the Middle Ages. It required a repudiation of some Aristotelian principles for the sciences and the arts to free themselves for the discovery of modern scientific laws and empirical methods. The medieval English poet Chaucer describes his student as being happy by having
                     At his bedded hed
Twenty books clothed in blake or red
Of એરિસ્ટોટલ and his philosophie
The Italian poet Dante says of એરિસ્ટોટલ in the first circles of hell,
I saw the Master there of those who know,
Amid the philosophic family,
By all admired, and by all reverenced;
There પ્લેટો too I saw, and સોક્રેટિસ,
Who stood beside him closer than the rest.

The German philosopher Friedrich Nietzsche has been said to have taken nearly all of his political philosophy from એરિસ્ટોટલ. However implausible this is, it is certainly the case that એરિસ્ટોટલ's rigid separation of action from production, and his justification of the subservience of slaves and others to the virtue - or arete - of a few justified the ideal of aristocracy. It is Martin Heidegger, not Nietzsche, who elaborated a new interpretation of એરિસ્ટોટલ, intended to warrant his deconstruction of scholastic and philosophical tradition. More recently, Alasdair MacIntyre has attempted to reform what he calls the Aristotelian tradition in a way that is anti-elitist and capable of disputing the claims of both liberals and Nietzscheans. Ayn Rand considered એરિસ્ટોટલ to be her only significant influence.

Notes and References

વધુ વાંચો 
The secondary literature on એરિસ્ટોટલ is vast. The following references are only a small selection.
 Ackrill J. L. 2001. Essays on પ્લેટો and એરિસ્ટોટલ, Oxford University Press, USA
  A popular exposition for the general reader.
 Bakalis Nikolaos. 2005. Handbook of Greek Philosophy: From Thales to the Stoics Analysis and Fragments, Trafford Publishing ISBN 1-4120-4843-5
 Barnes J. 1995. The Cambridge Companion to Aristotle, Cambridge University Press
 
 Bolotin, David (1998). An Approach to Aristotle's Physics: With Particular Attention to the Role of His Manner of Writing. Albany: SUNY Press. A contribution to our understanding of how to read Aristotle's scientific works.
 Burnyeat, M. F. et al. 1979. Notes on Book Zeta of Aristotle's Metaphysics. Oxford: Sub-faculty of Philosophy
 Chappell, V. 1973. Aristotle's Conception of Matter, Journal of Philosophy 70: 679-696
 Code, Alan. 1995. Potentiality in Aristotle's Science and Metaphysics, Pacific Philosophical Quarterly 76
 Frede, Michael. 1987. Essays in Ancient Philosophy. Minneapolis: University of Minnesota Press
 Gill, Mary Louise. 1989. Aristotle on Substance: The Paradox of Unity. Princeton: Princeton University Press
 
 Halper, Edward C. (2007) One and Many in Aristotle's Metaphysics, Volume 1: Books Alpha — Delta, Parmenides Publishing, ISBN 978-1-930972-21-6
 Halper, Edward C. (2005) One and Many in Aristotle's Metaphysics, Volume 2: The Central Books, Parmenides Publishing, ISBN 978-1-930972-05-6
 Irwin, T. H. 1988. Aristotle's First Principles. Oxford: Clarendon Press
 Jori, Alberto. 2003. Aristotele, Milano: Bruno Mondadori Editore (Prize 2003 of the "International Academy of the History of Science") ISBN 88-424-9737-1
 Knight, Kelvin. 2007. Aristotelian Philosophy: Ethics and Politics from Aristotle to MacIntyre, Polity Press.
 Lewis, Frank A. 1991. Substance and Predication in Aristotle. Cambridge: Cambridge University Press.
 Lloyd, G. E. R. 1968. Aristotle: The Growth and Structure of his Thought. Cambridge: Cambridge Univ. Pr., ISBN 0-521-09456-9.
 Lord, Carnes. 1984. Introduction to The Politics, by Aristotle. Chicago: Chicago University Press.
 Loux, Michael J. 1991. Primary Ousia: An Essay on Aristotle's Metaphysics Ζ and Η. Ithaca, NY: Cornell University Press
 Owen, G. E. L. 1965c. The Platonism of Aristotle, Proceedings of the British Academy 50 125-150. Reprinted in J. Barnes, M. Schofield, and R. R. K. Sorabji (eds.), Articles on Aristotle, Vol 1. Science. London: Duckworth (1975). 14-34
 Pangle, Lorraine Smith (2003). Aristotle and the Philosophy of Friendship. Cambridge: Cambridge University Press. Aristotle's conception of the deepest human relationship viewed in the light of the ઇતીહાસ of philosophic thought on friendship.
 Reeve, C. D. C. 2000. Substantial Knowledge: Aristotle's Metaphysics. Indianapolis: Hackett.
 
  An classic overview by one of Aristotle's most prominent English translators, in print since 1923.
 Scaltsas, T. 1994. Substances and Universals in Aristotle's Metaphysics. Ithaca: Cornell University Press.
 Strauss, Leo. "On Aristotle's Politics" (1964), in The City and Man, Chicago; Rand McNally.
 
  For the general reader.
 Woods, M. J. 1991b. "Universals and Particular Forms in Aristotle's Metaphysics." Oxford Studies in Ancient Philosophy supplement. 41-56

આ પણ વાંચો 
 Aristotelian ethics
 Aristotelian ભૌતિક વિજ્ઞાન
 Aristotelian view of God
 Aristotelianism
 Conimbricenses
 Hylomorphism
 List of teachings attributed to Aristotle
 Philia
 Phronesis
 Potentiality and actuality (Aristotle)

બાહ્ય કડિઓ

Collections of Aristotle's works 
 Massachusetts Institute of Technology  - primarily in English
 P. Remacle's collection - primarily Greek texts
 Project Gutenberg - English texts
 Tufts University - at the Perseus Project, in both English and Greek
 University of Adelaide  - primarily in English
 Timeline of Aristotle's life

તેમના પર લેખો 
 The Catholic Encyclopedia (general article)
 The Internet Encyclopedia of Philosophy  (general article)
 Scholarly surveys of focused topics from the Stanford Encyclopedia of Philosophy: articles on Aristotle, Aristotle in the Renaissance, Biology, Causality, Commentators on Aristotle, Ethics, Logic, Mathematics, Metaphysics, Natural philosophy, Non-contradiction, Political theory, Psychology, Rhetoric