First principle foundationalist system of philosophy. He used the "method of doubt", now called Cartesian doubt, to systematically doubt everything he could possibly doubt, until he was left with what he saw as purely indubitable truths. Using these self-evident propositions as his axioms, or foundations, he went on to deduce his entire body of knowledge from them. The foundations are also called "a priori" truths. His most famous proposition is "Je pense, donc je suis." ("I think, therefore I am", or "Cogito ergo sum") Descartes describes the concept of a first principle in the following excerpt from the preface to the "Principles
Mr. Cogito Laments On The Pettiness of Dreams"), "Pan Cogito a poeta w pewnym wieku" ("Mr. Cogito And A Poet Of A Certain Age"), "Pan Cogito a pop" ("Mr Cogito And Pop Music"), "Pan Cogito o magii" ("Mr. Cogito On Magic"), "Pan Cogito spotyka w Luwrze posążek Wielkiej Matki" ("Mr. Cogito Encounters A Figurine Of The Great Mother In The Louvre"), "Pan Cogito opowiada o kuszeniu Spinozy" ("Mr. Cogito Narrates The Temptation Of Spinoza"), "Pan Cogito otrzymuje czasem dziwne listy" ("Mr Cogito Occasionally Receives Strange Letters"), "Rozmyślania Pana Cogito o odkupieniu" ("Mr Cogito's Meditations On Redemption"), "Pan Cogito szuka rady" ("Mr. Cogito