INTRODUCTION TO THE THEÆTETUS.
Theodorus, a famous geometrician of Cyrene and a follower of Protagoras, is represented to have met Socrates at Athens, and to have been asked by him whether among his pupils there were any who promised to become eminent. Theodorus particularizes one above all the rest, who, while he is speaking, is seen approaching. His name is Theætetus. Socrates, having heard him so highly spoken of by Theodorus, at once opens upon the subject which he wishes to discuss, and asks What science is. Theætetus, in answer, enumerates several particular sciences, but is soon led to understand that the question is not, how many sciences there are, but what science itself is; and by an instance in point shews that he does so. Still he doubts his own ability to answer the question proposed, but is at length induced to make the attempt by Socrates pleasantly describing himself as inheriting his own mother's skill in midwifery, by which he is able to bring to the birth and deliver the mental conceptions of those whose souls are pregnant with ideas[1]
Theætetus, then, first of all says that science is nothing else than perception. This, Socrates observes, is the opinion of Protagoras, differently expressed; for he said, that man is the measure of all things, in other words that all things are such as they appear to each person. In order to examine the truth of this doctrine Socrates begins by stating it more fully. Protagoras asserts that nothing exists of itself, nor can any thing be designated by any quality, for what we call great will, in reference to something else, be also small, and what we call heavy, light, and so on, so that nothing ever exists but is always becoming. Consequently all things spring from motion, and the relation that they bear to each other. Thus, with respect to colour, it does not actually exist, it is neither, in the
- ↑ § 1–22.
