What was Aristotle's main interest?

Aristotle lectured on nearly every branch of learning: biology, medicine, anatomy, psychology, meteorology, physics, chemistry, mathematics, music, metaphysics, rhetoric, political science, ethics, literary criticism. Apparently an inspiring teacher, Aristotle encouraged his followers to conduct research in numerous fields of specialized knowledge. For example, he had student researchers compile reports1 on the systems of government of 158 Greek states. He also worked out a sophisticated system of logic for precise argumentation.-_-