for so long a period must also be held responsible for their undoubting acceptance of them.
Aristotle’s method in Physics, as in most other subjects, consisted in this: he first endeavoured to state clearly to himself what was the problem which he had before him, then he collected all the solutions of that problem which had been proposed by his predecessors, and all popular “sayings” and “notions” in regard to it, and then he examined existing opinions by the light of such facts as occurred to him, or which had been previously collected by him, or else he applied logical reasonings and general philosophical considerations in pronouncing upon the validity of the theories of others. A main part of the process consisted in starting ingenious difficulties to the theories in question, so that they seldom came through the ordeal without being wholly exploded or considerably modified. The residuum left, or the new result arrived at, constituted the theory of Aristotle. Such is not the procedure by which discoveries are made, knowledge increased, and the boundaries of science extended, in modern times. But after all, it was not a bad procedure for a man who was writing an encyclopædia. Aristotle had undertaken to set forth every department of knowledge revised and perfected, so far as possible, by the aid of stores of information and thought which he had laid up. In some departments he was much stronger than others: in Politics, Sociology, Psychology, and Natural History, he had a far better array of facts than in Astronomy and Mechanics. No one could be keener than he was to make facts the basis of every theory; but he was
