THE USE OF HYPOTHESIS. 133 



of combinations and permutations, it became apparent 

 that we could never cope with the possible variety of 

 nature. An exhaustive examination of the metallic alloys, 

 or chemical compounds which can be formed, was found 

 to be out of the question (vol. i. p. 218). It is on such 

 considerations that we can explain the very small addi- 

 tions made to our knowledge by the alchemists. Many 

 of them were men of the greatest acuteness, and their 

 indefatigable labours were pursued through many cen- 

 turies. A few of the more common compounds and 

 phenomena were discovered by them, but a true insight 

 into the principles of nature, now enables chemists to 

 discover far more useful facts in a single year than were 

 yielded by the alchemists during many centuries. There 

 can be no doubt that Newton was really an alchemist, and 

 often spent his days and nights in laborious experiments. 

 But in trying to discover the secret by which gross 

 metals might be rendered noble, his lofty powers of 

 deductive investigation were wholly useless. Deprived 

 of all guiding clues, his experiments must have been, like 

 those of all the alchemists, purely tentative and hap- 

 hazard. While his hypothetical and deductive investiga- 

 tions have given us the true system of nature, and opened 

 the way in almost every one of the great branches of 

 natural philosophy, the whole results of his tentative 

 experiments are comprehended in a few happy guesses, 

 given in his celebrated ' Queries/ 



Even when we are engaged in apparently passive 

 observation of a phenomenon, which we cannot modify 

 experimentally, it is advantageous that our attention 

 should be guided by some theoretical anticipations. A 

 phenomenon which seems simple is, in all probability, 

 really complex, and unless the mind is actively engaged 

 in looking for particular details, it is quite likely that the 

 most critical circumstances will be passed over. Bessel 



