plainly appear, even to the eyes of those who contradicted him.  As for himself, when he undertook to discourse of anything, he always began by the most common and universally received propositions, and was wont to say, that the strength of the argumentation consisted in so doing.  And, indeed, of all the men I have ever seen, I know none who could so easily bring others to own the truth of what he had a mind to prove to them.  And he said that Homer, speaking of Ulysses, called him “the certain or never-failing orator,” because he had the art of supporting his arguments upon principles that were acknowledged by all men.

Chapter VII.  Method to be observed in study.—­Arts and sciences no further useful, than they contribute to render men wiser, better, or happier.—­Vain and unprofitable knowledge to be rejected.

I presume now, that what I have said has been a sufficient evidence of the frankness and sincerity with which Socrates conversed with his friends, and made known his opinions to them.  It remains now that I should say something of the extreme care Socrates showed for the advancement of his friends, and how much he had at heart that they might not be ignorant of anything that could be useful to them, to the end they might not want the assistance of others in their own affairs.  For this reason, he applied himself to examine in what each of them was knowing; then, if he thought it in his power to teach them anything that an honest and worthy man ought to know, he taught them such things with incredible readiness and affection; if not, he carried them himself to masters who were able to instruct them.  But he resolved within himself how far a person who was well-educated in his studies ought to learn everything.

Thus for geometry he said, that we ought to know enough of it not to be imposed upon in measure when we buy or sell land, when we divide an inheritance into shares, or measure out the work of a labourer, and that it was so easy to know this, that if a man applied himself ever so little to the practice of such things, he would soon learn even the extent and circumference of the whole earth, and how to measure it; but he did not approve that a man should dive into the very bottom of this science, and puzzle his brains with I know not what figures, though he himself was expert in it, for he said he could not see what all those niceties and inventions were good for, which take up the whole life of a man, and distract him from other more necessary studies.