Wisdom, then, is distributed by most people, and indeed by us, into three parts. First therefore, if you please, let us consider the researches that have been made into the nature of things. Is there any one so puffed up with a false opinion of himself as to have persuaded himself that he knows those things? I am not asking about those reasons which depend on conjecture, which are dragged every way by discussions, and which do not admit any necessity of persuasion. Let the geometricians look to that, who profess not to persuade men to believe them, but to compel them to do so; and who prove to you everything that they describe. I am not asking these men for those principles of the mathematicians, which, if they be not granted, they cannot advance a single step; such as that a point is a thing which has no magnitude,—that an extremity or levelness, as it were, is a space which has no thickness,—that a line is length without breadth. Though I should grant that all these axioms are true, if I were to add an oath, do you think a wise man would swear that the sun is many degrees greater than the earth, before Archimedes had, before his eyes, made out all those calculations by which it is proved? If he does, then he will be despising the sun which he considers a god. But if he will not believe the mathematical calculations which employ a sort of constraint in teaching,—as you yourselves say,—surely he will be very far from believing the arguments of philosophers; or, if he does believe any such, which school will he believe? One may explain all the principles of natural philosophers, but it would take a long time: I ask, however, whom he will follow? Suppose for a moment that some one is now being made a wise man, but is not one yet,—what system and what school shall he select above all others? For, whatever one he selects, he will select while he is still unwise. But grant that he is a man of godlike genius, which of all the natural philosophers will he approve of above all others? For he cannot approve of more than one. I will not pursue an infinite number of questions; only let us see whom he will approve of with respect to the elements of things of which all things are composed; for there is a great disagreement among the greatest men on this subject.