Theaetetus replies, that knowledge is what he learns of Theodorus, i.e. geometry and arithmetic; and that there are other kinds of knowledge--shoemaking, carpentering, and the like. But Socrates rejoins, that this answer contains too much and also too little. For although Theaetetus has enumerated several kinds of knowledge, he has not explained the common nature of them; as if he had been asked, 'What is clay?' and instead of saying 'Clay is moistened earth,' he had answered, 'There is one clay of image-makers, another of potters, another of oven-makers.' Theaetetus at once divines that Socrates means him to extend to all kinds of knowledge the same process of generalization which he has already learned to apply to arithmetic. For he has discovered a division of numbers into square numbers, 4, 9, 16, etc., which are composed of equal factors, and represent figures which have equal sides, and oblong numbers, 3, 5, 6, 7, etc., which are composed of unequal factors, and represent figures which have unequal sides. But he has never succeeded in attaining a similar conception of knowledge, though he has often tried; and, when this and similar questions were brought to him from Socrates, has been sorely distressed by them. Socrates explains to him that he is in labour. For men as well as women have pangs of labour; and both at times require the assistance of midwives. And he, Socrates, is a midwife, although this is a secret; he has inherited the art from his mother bold and bluff, and he ushers into light, not children, but the thoughts of men. Like the midwives, who are 'past bearing children,' he too can have no offspring--the God will not allow him to bring anything into the world of his own. He also reminds Theaetetus that the midwives are or ought to be the only matchmakers (this is the preparation for a biting jest); for those who reap the fruit are most likely to know on what soil the plants will grow. But respectable midwives avoid this department of practice--they do not want to be called procuresses. There are some other differences between the two sorts of pregnancy. For women do not bring into the world at one time real children and at another time idols which are with difficulty distinguished from them. 'At first,' says Socrates in his character of the man-midwife, 'my patients are barren and stolid, but after a while they "round apace," if the gods are propitious to them; and this is due not to me but to themselves; I and the god only assist in bringing their ideas to the birth. Many of them have left me too soon, and the result has been that they have produced abortions; or when I have delivered them of children they have lost them by an ill bringing up, and have ended by seeing themselves, as others see them, to be great fools. Aristides, the son of Lysimachus, is one of these, and there have been others. The truants often return to me and beg to be taken back; and