If Thales was the first of all the great Greek philosophers, Plato must remain the best known of all the Greeks. His original name was Aristocles, but in his school days he received the nickname Platon (meaning "broad") because of his broad shoulders. Plato was born in Athens, about 427 B.C., and died there about 347 B.C. In early life Plato saw war service and had political ambitions. However, he was never really in agreeance with the Athenian democracy and could not join sincerely in its government. He was a devoted follower of Socrates, whose student he became in 409 B.C. The execution of that philosopher by the democrats in 399 B.C. was a crushing blow. Plato left Athens, believing that until "kings were philosophers or philosophers were kings" things would never go well with the world.
Like Socrates, Plato was mainly interested in moral philosophy and despised natural philosophy (that is, science) as an inferior and unworthy sort of knowledge. He was fond of mathematics because of its abstractions and its separation from the material. He believed that mathematics in its ideal form could still be applied to the heavens. The heavenly bodies, as he thought to be true, were in perfect geometric form; he decided also that since the heavens were perfect, the various heavenly bodies would have to move in exact circles. Also in mathematics, Plato's name is attached to the Platonic solids. In the Timaeus there is a mathematical construction of the elements (earth, fire, air, and water), in which the cube, tetrahedron, octahedron, and icosahedron are given as the shapes of the atoms of earth, fire, air, and water. The fifth Platonic solid, the dodecahedron, is Plato's model for the whole universe. .
In Plato's great writing "The Republic" he speaks of what he believes to be an ideal society. Plato invented a new hierarchy, which he thought fit for an almost perfect civil structure. On top was the philosophers, or philosopher/kings.
