1 10 008 MIC PUILOSOPH Y. [pt. i. 



might have replied, and in fact did reply, that it is because 

 their motion is nninterfered with. On the other hand 

 Kepler's theorem, that planetary motion is elliptical and 

 rhythmically accelerated and retarded although motion is 

 naturally rectilinear and uniform, left an unexplained residual 

 phenomenon. As an explanation it was true, hut it was 

 incomplete. When asked why the planets do not move in 

 straight lines with uniform velocity, Kepler recognized a 

 difficulty which must be explained, and which he tried to 

 solve. In his perplexity he had recourse to the subjective 

 method, and suggested that the planets were perhaps living 

 animals moved by their own volitions, or else that, as many 

 of the Christian Fathers thought, they were controlled in 

 their movements by presiding archangels. Could we read 

 all the unwritten annals of that time, we should doubtless 

 find that many educated persons rejected Kepler's discoveries 

 on account of this unexplained residuum ; attaching a 

 highei value to the mutual congruity of a set of conceptions 

 than to their verification. And in fact we know that many 

 refused to accept the discovery of the accelerated and 

 retarded motion of the planets, on the subjective ground 

 that it was " undignified " for heavenly bodies to hurry and 

 slacken their pace according to Kepler's law. 1 Now mark 

 the different behaviour of the objective method. Attaching 

 a higher value to ascertained conformity with observation 

 than to any presumed subjective congruity of conceptions, 

 Newton recognized the "unnatural" elliptic motion of the 



1 On similar grounds the Aristotelians denied the existence of the solar 

 spots ; it being impossible "that the Eye of the Universe should suffer from 

 ophthalmia." See Proctor, The Sun, p. 163. — " How can we admit thf.t 

 Nature could so restrict herself as to form all organic and inorganic combina- 

 tions in the mould of four substances, chosen at hazard, — hydrogen, hydro- 

 chloric acid, water, and ammonia, — and to produce nothing but variations on 

 these four themes?" Remark of Kolbe, cited in Wurtz, Introduction to 

 Chemical Phihsojihy, p. 97. — And in like manner we sometimes hear silly 

 people reject the Darwinian theory on grounds of "dignity," — it being sup- 

 posed that we are, in some incomprehensible way, "degraded" by the dia« 

 cov. ry that our remote ancestors were dumb beasts. 



