great period of Athens is not scientifically of the highest importance. Aristotle, to be sure, and his pupil Theophrastus, contributed very greatly to sound knowledge of animals, plants, and rocks, but in the theoretical sciences vague ideas based upon words rather than phenomena or clear and precise concepts led them astray.
"The most conspicious example," says Bacon, "of the first class [i. e., of the Rational School of Philosophers] was Aristotle, who corrupted natural philosophy by his logic: fashioning the world out of categories; assigning to the human soul, the noblest of substances, a genus from words of the second intention; doing the business of density and rarity (which is to make bodies of greater or less dimensions—that is, occupy greater or less spaces), by the frigid distinction of act and power; asserting that single bodies have each a single and proper motion, and that if they participate in any other, then this results from an external cause; and imposing countless other arbitrary restrictions on the nature of things; being always more solicitous to provide an answer to the question and affirm something positive in words than about the inner truth of things; a failing best shown when his philosophy is compared with other systems of note among the Greeks. For the Homœomera of Anaxagoras; the Atoms of Leucippus and Democritus; the Heaven and Earth of Parmenides; the Strife and Friendship of Empedocles; Heraclius's doctrine how bodies are resolved into the indifferent nature of fire, and remolded into solids; have all of them some taste of the natural philosopher—some savor of the nature of things, and experience, and bodies; whereas, in the physics of Aristotle you hear hardly anything but the words of logic; which in his metaphysics also, under a more imposing name, and more, forsooth, as a realist than a nominalist, he has handled over again. Nor let any weight be given to the fact that in his books on animals and his problems, and other of his treatises, there is frequent dealing with experiments. For he had come to his conclusion before; he did not consult experience, as he should have done, in order to do the framing of his decisions and axioms; but, having first determined the question according to his will, he then resorts to experience, and, bending her into conformity with his placets, leads her about like a
