Two historians flourished during Greece's classical age: Herodotus and Thucydides. Herodotus is commonly called the father of history, and his "History" contains the first truly literary use of prose in Western literature. Of the two, Thucydides was the more careful historian. His critical use of sources, inclusion of documents, and laborious research made his History of the Peloponnesian War a significant influence on later generations of historians. The greatest achievement of the 4th century was in philosophy. There were many Greek philosophers, but three names tower above the rest: Socrates, Plato, and Aristotle. These have had a profound influence on Western society.