Democritus (460 BC - 370 BC)

The first thinker to realize the Milky Way is composed of distant bright celestial bodies and to suggest the universe includes numerous worlds, Democritus states that the world is eternal and consists of various imperishable, indivisible elements called atoms. The real properties of atoms determine the perceived properties of matter, which turns out to be quite difficult to discover since the perception through the senses is subjective. Democritus emphasizes the epistemological and ethical importance of reason. Rational interpretation of sense data helps grasp the truth, while rational control of emotions and instincts allows people to fulfill themselves as strong characters: "The brave man is he who overcomes not only his enemies but also his pleasures."