THREE:"Didn't you hear something?" she whispered.In the theory of reasoning the simple proposition is taken as a starting-point; but instead of deducing the syllogism379 from the synthesis of two premises, Aristotle reaches the premises through the conclusion. He tells us, indeed, that reasoning is a way of discovering from what we know, something that we did not know before. With him, however, it is really a process not of discovery but of proof. He starts with the conclusion, analyses it into predicate and subject or major and minor, and then, by a further analysis, introduces a middle term connecting the two. Thus, we begin with the proposition, Caius is mortal, and prove it by interpolating the notion humanity between its two extremes. From this point of view the premises are merely a temporary scaffolding for bringing the major and minor into connexion with the middle term; and this is also the reason why Aristotle recognises three syllogistic figures only, instead of the four admitted by later logicians. For, the middle may either be contained in one extreme and contain the other, which gives us the first figure; or it may contain both, which gives the second figure; or be contained in both, which gives the third; and this is an exhaustive enumeration of the possible combinations.274
THREE:It might have been expected that, on reaching physiology, the Stagirite would stand on firmer ground than any of his contemporaries. Such, however, is not the case. As already observed, his achievements belong entirely to the dominion of anatomy and descriptive zoology. The whole internal economy of the animal body is, according to him, designed for the purpose of creating and moderating the vital heat;315 and in apportioning their functions to the different organs he is entirely dominated by this fundamental error. It was a common notion among the Greeks, suggested by sufficiently obvious considerations, that the brain is the seat of the psychic activities. These, however, Aristotle transports to the heart, which, in his system, not only propels the blood through the body, but is also the source of heat, the common centre where the different special sensations meet to be compared, and the organ of imagination and of passion. The sole function of the brain is to cool down the blooda purpose which the lungs also subserve. Some persons believe that air is a kind of food, and is inhaled in order to feed the internal fire; but their theory would involve the absurd consequence that all animals breathe, for all have some heat. Anaxagoras and Diogenes did, indeed, make that assertion, and the latter even went so far as to say that fish breathe with their gills, absorbing the air held in solution by the water passed through thema misapprehension, says Aristotle, which arose from not having studied the final cause of respiration.201 His physiological theory of generation is equally unfortunate. In accordance with his metaphysical system, hereafter to be explained, he distinguishes two elements in the reproductive process, of which one, that contributed by the male, is exclusively formative; and the other, that contributed by the female, exclusively material. The prevalent opinion was evidently, what we know now to be true, that each parent has both a formative and a material share in the composition of the embryo. Again, Aristotle, strangely enough, regards the generative element in both sexes as an unappropriated portion of the animals nutriment, the last and most refined product of digestion, and therefore not a portion of the parental system at all; while other biologists, anticipating Mr. Darwins theory of pangenesis in a very wonderful manner, taught that the semen is a con316flux of molecules derived from every part of the body, and thus strove to account for the hereditary transmission of individual peculiarities to offspring.202
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