An accurate timeline of when Aristotle made certain discoveries is not available. He began his training in philosophy in 367 B.C. and stayed in Plato's academy until around 347 B.C. It was during this time that he showed an interest in medicine, science and metaphysics.
Over the course of his life, Aristotle made a number of discoveries. He knew that a seed or embryo grew into a plant or animal and believed that every living being had a soul. He went on to study subjects such as anatomy and the earth sciences and implemented religion into metaphysics. By the time he died in 322 B.C., Aristotle had written more than 200 papers, many of which are still highly respected today.