Petrography rock was affixed to a microscope slide and then ground so thin that light could be transmitted through mineral grains that otherwise appeared opaque. The position of adjoining grains was not disturbed, thus permitting analysis of rock texture. Thin section petrography became the standard method of rock study. Since textural details contribute greatly to knowledge of the sequence of crystallization of the various mineral constituents in a rock, petrography progressed into petrogenesis and ultimately into petrology. It was in Europe, principally in Germany, that petrography advanced in the last half of the nineteenth century. The macroscopic characters of rocks, those
What Is Literature? What Is Literature? What Is Literature? (), also published as "Literature and Existentialism",) is an essay by French philosopher and novelist Jean-Paul Sartre, published by Gallimard in 1948. Initially published in freestanding essays across French literary journals "Les Temps modernes", "Situations I" and "Situations II", essays "What is Writing?" and "Why Write?" were translated into English and published by the Paris-based literary journal Transition 1948. The English translation by Bernard Frechtman was published in 1950. Sartre attempts to devise an understanding of the effect literature has on those who are subjected to it. In the foreword Sartre addresses his critics