PROFESSOR LOVERIXG'S ADDRESS. 209 



His philosophy of zoology was published a few years after the cos- 

 mogony of Laplace ; in which the mathematician broaches the theory 

 of evolution as a mechanical doctrine, capable of explaining certain 

 characteristics of the solar system, about which the law of gravitation 

 is silent. Whoever reads the stately chapters of Laplace, on the sta- 

 bility of the planets and the safeguards of the comets, will easily recog- 

 nize expressions which are the mechanical equivalents of the princi- 

 ples of natural selection and the survival of the fittest. The elder 

 Herschel hazarded the speculation that the clusters of stars and the 

 nebulas which his devouring telescope had picked up, by hundreds, on 

 the verge of the visible heavens, were genuine suns assembled under 

 the organizing power of gravitation; and that the varieties in size, 

 shape, and texture, were produced by differences of age and distance. 

 The imagination of Herschel and other astronomers has taken a loftier 

 flight. To them many of the nebulae are not clusters of stars, but 

 unborn solar systems, waiting for that consolidation by which planets 

 are evolved and a central sun is formed, and destined thus to repeat 

 the cosmogony of the home system. Comte claims that he has raised 

 the nebular hypothesis to the rank of positive science. He supposes 

 the stupendous enginery of evolution to be reversed. He follows, with 

 his mathematics, the expanding sun backward into chaos, until it has 

 absorbed into its bosom even the first-born among the planets, and 

 finds, at every stage, numerical confirmation of what Laplace threw 

 out as a plausible conjecture. As Mr. Mill and other writers of note 

 have accepted this authority, it should be understood that Comte has 

 never published the data or the process of his computations. By what- 

 ever other inspiration he arrived at his conclusion, he was not brought 

 to it by his mathematics. He has said all that is necessary to show 

 that he ignored all the difficulties of the problem, and dodged the only 

 solution that could give satisfaction. The cosmogony of Laplace, with 

 all its fascination, must be excluded from exact mechanics and re- 

 manded back to its original place in natural history, by the side of the 

 more general nebular hypothesis of Herschel. All other cosmogo- 

 nies which poetry or science have invented are childish in comparison 

 with this; and no one would desire to banish it from science alto- 

 gether, until it is disproved or displaced by. something better. In- 

 stead of deciding, it must share the fate of the all-embracing cosmical 

 speculation of Halley. How uncertain that fate is we may be taught 

 by the frequency with which the preponderance of evidence has shifted 

 from one side to the other, during the last fifty years. The irresolva- 

 bility of many of the nebula?, by powerful telescopes, led Herschel to 

 espouse the cause of a diffuse primeval matter, out of which worlds 

 were fashioned. No wonder that, in particular cases, the negative 

 evidence was sometimes turned into positive evidence on the other 

 side, by improvements in telescopes. Although every nebula which 

 deserted from the nebular hypothesis strengthened the suspicion that 

 vol. vi. 14 



