If we go back to school and think of the "trouble kid", the friend who gets us into trouble, the one who complicates everything, we might think of René Descartes in this way ! Until his works, the world of philosophy was guided by natural thinking: we can think about the things we see and trust our thoughts. Philosophy moved from the object that appeared to the subject that thought it. After Descartes, there is a big turning point, because after him, we cannot naturally trust our mind, we have to put everything in brackets, doubt everything and we are the constructors of reality, philosophy moves from the subject which think about object thinking, and it's a big problem! But this discussion of this problem goes too far from our porpoise in this brief biography. He is the hinge that closes the door to the medieval world and opens the modern one! Born in La Haye in Touraine (today this small town is called Descartes), Indre-et-Loire, France on March 31, 1596 of a noble family: Joachim, lawyer, and Jeanne, who died when he was thirteen month. He spent his early years with his grandmother and his older brother and sister, Pierre and Jeanne. Little Descartes grew up in a careful environment given his sickly nature. At the age of 8, he moved to La Flèche to attend the prestigious Jesuit school until 1614, where he studied grammar, Latin and Greek, classical literature in depth, physics and mathematics , and will also be imbued with philosophy. of Aristotle, but already filtered by the scholastic vision. At that time, the city and the intellectual world around it were moved by the discovery of Jupiter's moons by Galileo Galileo, in 1610. Like his father and some...... middle of paper ...... Science, mathematics, physics, biology and geometry break away from the core of philosophy and begin their journey as a separate science. But more deeply, he is the founder of Idealism, the system that begins a new era in philosophy, because in ancient and medieval philosophy we believe in the existence of things, res, by themselves, independent of me . ; but with Descartes, we begin to believe in the existence of things only if they are linked to me, if they exist in my mind, thus giving birth to a new way of seeing life, a new way of approaching the world, which would later materialize in the French Revolution, where personal beliefs trumped God-given beliefs. In conclusion, Descartes is one of the greatest thinkers of all time, changing the way we see the world, the way we understand religion, funding new ways of understanding objects, etc...