"Plato (c. 427 BC – c. 347 BC) was an immensely influential classical Greek philosopher, student of Socrates, teacher of Aristotle, writer, and founder of the Academy in Athens....

...In Plato's writings one finds debates concerning the best possible form of government, featuring adherents of aristocracy, democracy, monarchy, and others. A central theme is the one between nature and convention, concerning the role of heredity and environment in human intelligence and personality...

...Plato wrote mainly in the form of dialogues. In the early ones several characters discuss a topic by asking questions of one another. Socrates figures prominently and a lively, more disorganized form of elenchos/dialectic is perceived; these are called the Socratic Dialogues.

But the qualities of the dialogues changed a great deal over the course of Plato's life. It is generally agreed that Plato's earlier works are more closely based on Socrates' thoughts, whereas his later writing increasingly breaks away from the views of his former teacher....

...One of Plato's legacies, and perhaps his greatest, was his dualistic metaphysics, often called (in metaphysics) Platonism or (Exaggerated) Realism. Plato's metaphysics divides the world into two distinct aspects: the intelligible world of "forms" and the perceptual world we see around us. He saw the perceptual world, and the things in it, as imperfect copies of the intelligible forms or ideas. These forms are unchangeable and perfect, and are only comprehensible by the use of the intellect or understanding (i.e., a capacity of the mind that does not include sense-perception or imagination)....

...Plato's thought is often compared with that of his most famous student, Aristotle, whose reputation during the western Middle Ages so completely eclipsed that of Plato that the Scholastic philosophers referred to Aristotle as "the Philosopher"....

...Only in the Renaissance, with the general resurgence of interest in classical civilization, did knowledge of Plato's philosophy become more widespread again in the West. Many of the greatest early modern scientists and artists who broke with Scholasticism and fostered the flowering of the Renaissance, with the support of the Plato-inspired Lorenzo de Medici, saw Plato's philosophy as the basis for progress in the arts and sciences. By the 19th century Plato's reputation was restored and at least on par with Aristotle's.... (from Wikipedia.com)