From, A History of Greek Philosophy, vol. IV, Plato: the man and his dialogues, earlier period,
Cambridge University Press, 19896, pp. 8-38.
This brief preliminary survey οf the attention paid by Plato to previous and contemporary thought is intended as a reminder that the history of Greek philosophy represents, even in its greatest figures, a continuous progress. In this volume we are to study not a wholly new departure, but a climax, and it is essential to have the earlier stages in mind. This is not to belittle Plato. One does not impugn the greatness of an architect by naming the materials that he has used in the execution of a grand design, nor even, if he is a Wren, by studying classical and Renaissance architecture. In assessing the relationship between Plato and other thinkers, it is possible to be moved by a misguided partisanship, a feeling that to allow them any considerable influence over his mind is somehow to disparage his originality. In fact they provide important clues to it. This Ι believe to have been particularly true of his Pythagorean friends. Some critics would reduce Pythagoras to a kind of magician and his pre-Platonic followers to religious mystics with a set of irrational taboos and a superstitious reverence for numbers. On the contrary, their combination of religious with mathematical, scientific and political interests may furnish the key to the essential unity of Plato’s thought, which we mistakenly divide into logical, metaphysical, scientific or political compartments. Awareness οf this unity can only heighten our appreciation of the genius which achieved it.
A Day in Old Athens * A Short History of Greek Philosophy
The Greek Word Library
Reference address : https://www.ellopos.net/elpenor/greek-texts/ancient-Greece/guthrie-plato.asp?pg=24