Who is Aristotle from A History of Western Philosophy and what is their importance?

Aristotle was born in 384 BC at Stagyra, in Thrace. His father was a family physician to the king of Macedonia. He went to Athens and learnt from Plato, where he stayed for twenty years after Plato's death in 348-7 BC. His wife was Hermias's niece. In 343 BC he started teaching Alexander and some regard him as influential in Alexander's conquers.