Aristotle was the most renowned Ancient Greek philosopher for nearly 2,000 years, and his most famous work was on the art of persuasion. Aristotle is widely credited with being the forbearer of the study of the art of rhetoric. But Aristotle was far more than a philosopher, believe it or not. In addition to being interested in metaphysical issues like the soul and the subconscious, Aristotle also wrote a bunch of works about animals, constituting an ancient form of biology.