Greek philosophers were "seekers and lovers of wisdom". They studied and analyzed the world around them using logic and reason. Although we often think of philosophy as religion or "the meaning of life", the Greek philosophers were also scientists. Many studied mathematics and physics as well. Often the philosophers were teachers of wealthy children. Some of the more famous ones opened their own schools or academies.
Major Greek Philosophers
Socrates
Socrates was the first major Greek philosopher. He came up with the Socratic Method. This was a way of studying issues and problems through a question and answer technique. Socrates introduced political philosophy and got the Greeks to start thinking hard about morals, good and evil, and how their society should work. Socrates didn't write a lot down, but we know what he thought from the recordings of his student, Plato.
Plato
Plato wrote much of his philosophy in conversations called dialogues. The dialogues feature Socrates as one of the speakers. Plato's most famous work is called the Republic. In this work Socrates discusses the meaning of justice and how cities and governments should be ruled. He describes his ideal society in the conversations. This work is still studied today and has had an impact on both philosophy and political theory throughout history.
Plato from The School of Athens by Raffaello Sanzio.
Plato believed that no one should be rich or live in luxury. He also believed that each person should do the job that they are best suited for. He thought a philosopher-king should rule society. He founded his own school called the Academy where he taught students, such as Aristotle.
Aristotle
Aristotle was a student of Plato, but didn't necessarily agree with all that Plato said. Aristotle liked to focus on more practical areas of philosophy including science. He founded his own school called the Lyceum. He thought that reason was the highest good and that it was important to have self control. Aristotle was a tutor for Alexander the Great.
Other Greek Philosophers
Pythagoras - Pythagoras is most known for the Pythagorean Theorem which is used to find the length of sides of right triangles. He also believed that the world was based on mathematics.
Epicurus - Said that the gods had no interest in humans. That what we should do is enjoy our lives and be happy.
Zeno - Founded a type of philosophy called Stoicism. He said that happiness was from accepting whatever happened, good or bad. His philosophy was a way of life that emphasized a person's actions more than their words.