Sophie opens her next letter to find the philosopher is not upset about her breaking in, though he regrets he will have to move without explaining why. She begins reading about Aristotle, who the philosopher describes as Greece’s last great philosopher and Europe’s first biologist. Unlike Plato, his teacher, who was engrossed in the world of ideas, Aristotle was interested in natural processes in the material world. Aristotle examined every field of science and wrote encyclopaedic notes about his findings. Aristotle was also responsible for “categorizing concepts and found[ing] the discipline of Logic as a science” (106). He refuted Plato by asserting that forms or ideas only exist because of peoples’ experiences with them, and characteristics lay within things, not outside them in a mold. Furthermore, “nothing exists in consciousness that has not first been experienced by the senses” (107); in other words, the innate ideas suggested by Plato did not exist according to Aristotle. Aristotle also believed that people do have an innate capability to reason and categorize things in logical ways. However, this reason is dependent on the senses. He went further by separating the nature of things into “form” (the sum of the parts) and “substance” (what the whole is made of).