tion of the good which occupies the statesman or the moralist. In many ways this demarcation by Aristotle of the separate spheres of different Sciences, gave rise to great clearness of view.
The Logic of Science deals, as might be expected, with the method of defining things,—that is, of saying what they are. But we do not here find the scholastic idea of definition, per genus et differentiam, by stating the class to which a thing belongs, and the characteristic which separates it from the rest of that class. Aristotle takes the more real and thorough position that, to define a thing adequately, you must state its cause. “Science itself,” he says, “is knowledge of a cause.” But what is cause? There are four kinds: the “formal,” which is the whole nature of a thing, being the sum of the other three causes; the “material,” or the antecedents out of which the thing arises; the “efficient,” or motive power; and the “final,” or object aimed at. Speaking generally, the causes most in use for scientific definitions are the efficient and the final. We define an eclipse of the moon by its efficient cause,—the interposition of the earth. We define a house by its final cause,—a structure for the sake of shelter.
One quotation, as a specimen, may conclude these glimpses of the ‘Later Analytics,’ or Aristotle’s Logic of Science: “Nature,” he says, “presents a, perpetual cycle of occurrences. When the earth is wet with rain, an exhalation rises; when an exhalation rises, a cloud forms; when a cloud forms, ram follows, and the earth is saturated: so that the same term
