Whom did renaissance humanists study to increase their knowledge of different topics through reason?

Renaissance humanists studied various classical thinkers from ancient Greece and Rome, such as Plato, Aristotle, Cicero, and Seneca. They believed that by studying the works of these thinkers, they could gain a deeper understanding of a wide range of topics and improve their reasoning abilities. This emphasis on classical learning and reason was a key aspect of Humanism during the Renaissance.