Socrates

I know that I am intelligent, because I know that I know nothing.

Be slow to fall into friendship; but when thou art in, continue firm and constant.

Be as you wish to seem.

Socrates was born in Athens in the 5th century BCE. Athens was a center of  education, culture and philosophy. Philosophers of that time including him were traveling from across Greece to teach rhetoric, astronomy, cosmology, geometry, and other stuff related to philosophy and science.

Socrates learned that all virtue is knowledge and that no one desires what is bad.  If anyone does something that truly is bad, it must be consequence of unwillingly or ignorance.

Many of philosophical movements were inspired by Socrates and his younger associates. Socrates was the main interlocutor in Platos' dialogues. His most famous student was Aristotle. The philosophic movements  dominate in the intellectual life of the Roman empire were following Socrates' activity directly or indirectly. Muslim world in the 7th through 10th centuries CE were influenced by Socrates' philosophy, also the West as foundations of Medieval philosophy and the Renaissance.