180 INDUCTION. 



The facts being out of the reach of being observed, in any such man- 

 ner as would have enabled the senses to identify directly the path of 

 the planet, the conception requisite for framing a general description 

 of that path could not be collected by abstraction from the observations 

 themselves ; the mind had to supply hypothetically, from among the 

 conceptions it had obtained from other portions of its experience, some 

 one which would correctly represent the series of the observed facts. 

 It had to frame a supposition respecting the general course of the phe- 

 nomenon, and ask itself. If this be the general description, what will 

 the details be'? and then compare these with the details actually 

 observed. If they agreed, the hypothesis would serve for a descrip- 

 tion of the phenomenon : if not, it was necessarily abandoned, and 

 another tried. It is such a case as this which gives color to the doc- 

 trine that the mind, in framing the descriptions, adds something of its 

 own which it does not find in the facts. 



Yet it is a fact, surely, that the planet does describe an ellipse ; and 

 a fact which we could see, if we had adequate visual organs and a 

 suitable position. Not having these advantages, but possessing the 

 concejjtion of an ellipse, or (to express the meaning in less technical 

 language) knowing what an ellipse was, Kepler tried whether the ob- 

 served places of the planet were consistent with such a path. He 

 found they were so ; and he, consequently, asserted as a fact that the 

 planet moved in an ellipse. But this fact, which Kepler did not add 

 to, but found in, the motions of the planet, namely, that it occupied in 

 succession the various points in the circumference of a given ellipse, 

 was the very fact, the separate parts of which had been separately ob- 

 served ; it was the sum of the different observations. It superadded 

 nothing to the particular facts which it served to bind together: ex- 

 cept, indeed, the knowledge that a resemblance existed between the 

 planetary oi'bit and other ellipses ; an accession the nature and amount 

 of which will be fully considered hereafter.* 



Having stated this fundamental difference between my views and 

 those of Mr. Whewell, I must add, that his account of the manner in 

 which a conception is selected, suitable to express the facts, appears 

 to me perfectly- just. The experience of all thinkers will, I believe, 

 testify that the process is tentative ; that it consists of a succession of 

 guesses ; many being rejected, until one at last occurs fit to be chosen. 

 We know from Kepler himself that before hitting upon the " concep- 

 tion" of an ellipse, he tried nineteen other imaginaiy paths, which, 

 finding them inconsistent with the observations, he was obliged to re- 

 ject. But as Mr. Whewell truly says, the successflil hypothesis, 

 although a guess, ought not to be called a lucky, but a skillful guess. 

 The guesses which serve to give mental unity and wholeness to a 

 chaos of scattered particulars, are accidents which occur to no minds 

 but those abounding in knowledge and disciplined in scientific combi- 

 nations. 



How far this tentative method, so indipensable as a means to the col- 

 ligation of facts for pui^j^oses of description, admits of application to 

 Induction itself, and what functions belong to it in that department, 

 will be considered in the chapter of the present Book which relates to 

 Hypotheses. On the present occasion we have chiefly tc distinguish 



* Vide infra, book iv., ch. I. 



