en. v.] THE TWO METHODS. 107 



subjective method as exhibited in some of its more plausible 

 proceedings, if we would properly contrast it with the objective 

 method by which scientific discoveries are made. Let us do 

 so; and, as we have just now alluded to the discovery of the 

 law of gravitation as an instance of association of ideas 

 corroborated by the employment of the objective method, let 

 us choose our example from the history of that discovery. 

 Doubtless the reasoning seemed very sound and plausible to 

 the Greeks, which, starting from the assumptions that the 

 circle is the most perfect of figures, and that all motion is 

 naturally circular, proceeded to the inferences that the 

 planets move in circular orbits, and that their motion is 

 uniform. For twenty centuries this reasoning passed un- 

 challenged. Until Kepler's time no one thought it necessary 

 to make observations and ascertain whether, as a matter 

 of fact, the planetary orbits were circular ; nor previous to 

 Galileo did any one think of verifying the premise that all 

 motion is naturally circular ; nor did it occur to any one that 

 the conclusion might not inevitably follow from the premise, 

 — since the planets might, as in fact they do, move in an 

 orbit which is not the natural path of motion when uninterfered 

 with. Now mark how ill it fared with this subjective order 

 of conceptions as soon as it was confronted with the order of 

 phenomena. In the first place, Galileo proved, by reasoning 

 upon direct observations, that all motion is naturally recti- 

 linear, and not circular, — that, if you could set a body- 

 moving, apart from all disturbing conditions, it would go on 

 fv>r ever in a straight line. This destroyed the premise of the 

 subjective syllogism. Secondly, Kepler proved, by actual 

 observation, that the planets do not move in circular orbits, 

 with a uniform rate of velocity ; but that they move in 

 elliptic orbits, with a velocity which periodically increases 

 and diminishes. This upset the subjective conclusion. And 

 thirdly, the passage from premise to conclusion was seen to 

 have been wrongly made, since while the planets would 



