EVOLUTION OF THE SCIENTIFIC INVESTIGATOR 141 



infinitely greater than the dimensions of the earth's orbit. Even the 

 world of philosophy was not yet ready for this conception, and, so far 

 from seeing the reasonableness of the explanation, we find Ptolemy 

 arguing against the rotation of the earth on grounds which careful 

 observations of the phenomena around him would have shown to be 

 ill-founded. 



Physical science, if we can apply that term to an uncoordinated 

 body of facts, was successfully cultivated from the earliest times. 

 Something must have been known of the properties of metals, and 

 the art of extracting them from their ores must have been practiced, 

 from the time that coins and medals were first stamped. The pro- 

 perties of the most common compounds were discovered by alchem- 

 ists in their vain search for the philosopher's stone, but no actual 

 progress worthy of the name rewarded the practitioners of the black 

 art. 



Perhaps the first approach to a correct method was that of Archi- 

 medes, who by much thinking worked out the law of the lever, 

 reached the conception of the centre of gravity, and demonstrated 

 the first principles of hydrostatics. It is remarkable that he did not 

 extend his researches into the phenomena of motion, whether spon- 

 taneous or produced by force. The stationary condition of the human 

 intellect is most strikingly illustrated by the fact that not until the 

 time of Leonardo was any substantial advance made on his discovery. 

 To sum up in one sentence the most characteristic feature of ancient 

 and medieval science, we see a notable contrast between the precision 

 of thought implied in the construction and demonstration of geo- 

 metrical theorems and the vague indefinite character of the ideas of 

 natural phenomena generally, a contrast which did not disappear 

 until the foundations of modern science began to be laid. 



We should miss the most essential point of the difference between 

 medieval and modern learning if we looked upon it as mainly a differ- 

 ence either in the precision or the amount of knowledge. The devel- 

 opment of both of these qualities would, under any circumstances, 

 have been slow and gradual, but sure. We can hardly suppose that 

 any one generation, or even any one century, would have seen the 

 complete substitution of exact for inexact ideas. Slowness of growth 

 is as inevitable in the case of knowledge as in that of a growing organ- 

 ism. The most essential point of difference is one of those seemingly 

 slight ones, the importance of which we are too apt to overlook. It 

 was like the drop of blood in the wrong place, which some one has 

 told us makes all the difference between a philosopher and a maniac. 

 It was all the difference between a living tree and a dead one, between 

 an inert mass and a growing organism. The transition of knowledge 

 from the dead to the living form must, in any complete review of the 

 subject, be looked upon as the really great event of modern times. 



