ONE:It seems strange that Galileo, having gone so far, did not go a step further, and perceive that the planetary orbits, being curvilinear, must result from the combination of a centripetal with a tangential force. But the truth is that he never seems to have grasped his own law of inertia in its full generality. He understood that the planets could not have been set in motion without a rectilinear impulse; but his idea was that this impulse continued only so long as was necessary in order to give them their present velocity, instead of acting on them for ever as a tangential force. The explanation of this strange inconsequence must be sought in a survival of Aristotelian conceptions, in the persistent belief that rectilinear motion was necessarily limited and temporary, while circular motion was natural, perfect, and eternal.548 Now such conceptions as386 Nature, perfection, and eternity always rebel against an analysis of the phenomena wherein they are supposed to reside. The same prejudice will explain why Galileo should have so persistently ignored Keplers Laws, for we can hardly imagine that they were not brought under his notice.Our critics are not content with bringing up Aristotle as an authority on the metaphysical controversies of the present day, and reading into him theories of which he never dreamed:279 they proceed to credit him with modern opinions which he would have emphatically repudiated, and modern methods which directly reverse his scientific teaching. Thus Sir A. Grant takes advantage of an ambiguity in the word Matter, as used respectively by Aristotle and by contemporary writers, to claim his support for the peculiar theories of Prof. Ferrier; although the Stagirite has recorded his belief in the reality and independence of material objects (if not of what he called matter) with a positiveness which one would have thought left no possibility of misunderstanding him.168 And Mr. Wallace says that Aristotle recognises the genesis of things by evolution and development; a statement which, standing where it does, and with no more qualifications than are added to it, would make any reader not versed in the subject think of the Stagirite rather as a forerunner of Mr. Darwin and Mr. Herbert Spencer, than as the intellectual ancestor of their opponents; while, on a subsequent occasion, he quotes a passage about the variations of plants under domestication, from a work considered to be un-Aristotelian by the best critics, apparently with no other object than that of finding a piece of Darwinism in his author.169
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ONE:There was the sound of a faint scratching as if a mouse was working somewhere. The warder in the courtyard pronounced it to be a mouse and passed on. Then a figure, almost invisible in the gloom, crept along the top of the wall and dropped feet foremost into the street. It was nothing but luck that stood Ren Lalage in such good stead all along. A crumbling bit of plaster, some repairs going on in the gallery overhead, a ladder and a couple of gimlets left about by one of the carpenters engaged on the job.The Alexandrian Sceptics general arguments against the possibility of knowledge resolve themselves into a criticism of what Sir W. Hamilton called Natural Realism, somewhat complicated and confused by a simultaneous attack on the theory of natural morality conceived as something eternal and immutable. They are summed up in the famous ten Tropes. Of these the first three are founded on the conflicting sensations produced by the same object when acting on different animalsas is inferred from the marked contrast presented by their several varieties of origin and structure,on different men, and on the different senses of the same individual. The fourth, which has evidently an ethical bearing, enlarges on the changes in mens views caused by mental and bodily changes, according to their health, age, disposition, and so forth. The next five Tropes relate to circumstances connected with the objects themselves: their distance and position as regards the spectator, the disturbance produced in their proper action by external influences such as air and light, together with the various membranes and humours composing the organs of sense through which they are apprehended; their quantitative variation, involving as it does opposite effects on the senses, or as with medicines, on the health; the law of relativity, according to which many things are only known when taken in company with others, such as double and half, right and left, whole and part; comparative frequency or rarity of occurrence, as with comets, which, while really of much less importance than the sun, excite much more interest from their being so seldom seen. Finally, the tenth Trope is purely ethical, and infers the non-existence of a fixed moral standard from the divergent and even opposite customs prevailing among different nations.297
