One of the more lively passages is an attack on Democritus’ “void”: there can be no void or vacuum in nature, says Aristotle, for in a vacuum all bodies would fall with equal velocity; this being impossible, “the supposed void turns out to have nothing in it”—an instance at once of Aristotle’s very occasional humor, his addiction to unproved

One always feels towards logic as Virgil bade Dante feel towards those who have been damned because of their colorless neutrality: Non ragionam di lor, ma guarda e passa—“Let us think no more about them, but look once and pass on.”

The mathematical reader will see at once that the structure of the syllogism resembles the proposition that two things equal to the same thing are equal to each other; if A is B, and C is A, then C is B. As in the mathematical case the conclusion is reached by canceling from both premisses their common term, A; so in our syllogism the conclusion is

How shall we proceed to define an object or a term? Aristotle answers that every good definition has two parts, stands on two solid feet: first, it assigns the object in question to a class or group whose general characteristics are also its own—so man is, first of all, an animal; and secondly, it indicates wherein the object differs from all the

Chemical analysis, correct measurements and weights, and a thorough application of mathematics to physics, were unknown. The attractive force of matter, the law of gravitation, electrical phenomena, the conditions of chemical combination, pressure of air and its effects, the nature of light, heat, combustion, etc., in short, all the facts on which

The economic dependence of Plato’s guardians on the economic class would very soon reduce them to the controlled political executives of that class; even the manipulation of military power would not long forestall this inevitable issue—any more than the military forces of revolutionary Russia could prevent the development of a proprietary

an agricultural population is inclined to supernatural belief by its helpless dependence on the caprice of the elements, and by that inability to control nature which always leads to fear and thence to worship; when industry and commerce developed, a new type of mind and man arose, more realistic and terrestrial, and the power of the Church began

The vast majority will retain all respectable institutions—property, money, luxury, competition, and whatever privacy they may desire. They will have marriage as monogamic as they can bear; and all the morals derived from it and from the family; the fathers shall keep their wives and the mothers shall keep their children ad libitum and nauseam.

Plato underrated, we are told, the force of custom accumulated in the institution of monogamy, and in the moral code attached to that institution; he underestimated the possessive jealousy of males in supposing that a man would be content to have merely an aliquot portion of a wife; he minimized the maternal instinct in supposing that mothers would