Sentence:  <WSD>Aristotle</WSD> also tended to stratify all aspects of human nature and activity into levels of excellence and , like Plato , he put the pure and unimpassioned intellect on the top level . 
Meaning of the word marked with <WSD> tags:  one of the greatest of the ancient Athenian philosophers; pupil of Plato; teacher of Alexander the Great (384-322 BC)