Plato (c.429-347 BC.) Greek philosopher, son of Ariston and Perictione. His work owes much to the teachings of Socrates whose pursuit of knowledge was characterised by an attempt to apprehend the underlying essence of things beyond the many instances by which they were recognised or understood. In The Republic Plato elaborated the process proposing a series of unchanging forms which are causally related to the things to which they lend their name and which are comprehended through thought rather than sensed. To the form of 'the good', Plato attributed a special almost divine position, sustaining yet transcending the forms in general. The soul is, accordingly, immortal, and confirms the philosopher's positive view of religion: in The Republic atheists who resist conversion are to be executed.