LECTURES AND ESS A YS 



opposed to each other after all. In one 

 fundamental particular they at all events 

 agree. They equally imply the inter- 

 dependence and harmonious interaction 

 of parts, and the subordination of the in- 

 dividual powers of the universal organism 

 to the working of the whole. 



Never were the harmony and inter- 

 dependence just referred to so clearly 

 recognised as now. Our insight regard- 

 ing them is not that vague and general 

 insight to which our fathers had attained, 

 and which, in early times, was more 

 frequently affirmed by the synthetic poet 

 than by the scientific man. The inter- 

 dependence of our day has become 

 quantitative expressible by numbers 

 leading, it must be added, directly into 

 that inexorable reign of law which so 

 many gentle people regard with dread. 

 In the domain now under review men of 

 science had first to work their way from 

 darkness into twilight, and from twilight 

 into day. There is no solution of con- 

 tinuity in science. It is not given to 

 any man, however endowed, to rise 

 spontaneously into intellectual splendour 

 without the parentage of antecedent 

 thought. Great discoveries grow. Here, 

 as in other cases, we have first the seed, 

 then the ear, then the full corn in the 

 ear, the last member of the series imply- 

 ing the first. Thus, as regards the dis- 

 covery of gravitation with which the 

 name of Newton is identified, notions 

 more or less clear concerning it had 

 entered many minds before Newton's 

 transcendent mathematical genius raised 

 it to the level of a demonstration. The 

 whole of his deductions, moreover, rested 

 upon the inductions of Kepler. Newton 

 shot beyond his predecessors; but his 

 thoughts were rooted in their thoughts, 

 and a just distribution of merit would 

 assign to them a fair portion of the 

 honour of discovery. 



Scientific theories sometimes float like 

 rumours in the air before they receive 

 complete expression. The doom of a 

 doctrine is often practically sealed, and 

 the truth of one is often practically ac- 

 cepted, long prior to the demonstration 



of either the error or the truth. Per- 

 petual motion was discarded before it 

 was proved to be opposed to natural 

 law ; and, as regards the connection and 

 interaction of natural forces, intimations 

 of modern discoveries are strewn through 

 the writings of Leibnitz, Boyle, Hooke, 

 Locke, and others. 



Confining ourselves to recent times, 

 Dr. Ingleby has pointed out to me some 

 singularly sagacious remarks bearing 

 upon this question, which were published 

 by an anonymous writer in 1820. Roget's 

 penetration was conspicuous in 1829. 

 Mohr had grasped in 1837 some deep- 

 lying truth. The writings of Faraday 

 furnish frequent illustrations of his pro- 

 found belief in the unity of nature. " I 

 have long," he writes in 1845, " held an 

 opinion almost amounting to conviction, 

 in common, I believe, with other lovers 

 of natural knowledge, that the various 

 forms under which the forces of matter 

 are made manifest have one common 

 origin, or, in other words, are so directly 

 related and mutually dependent that 

 thsy are convertible, as it were, one 

 into another, and possess equivalence 

 of power in their action." His own 

 researches on magneto-electricity, on 

 electro-chemistry, and on the " magneti- 

 sation of light," led him directly to this 

 belief. At an early date Mr. Justice 

 Grove made his mark upon this question. 

 Colding, though starting from a meta- 

 physical basis, grasped eventually the 

 relation between heat and mechanical 

 work, and sought to determine it experi- 

 mentally. And here let me say, that 

 to him who has only the truth at heart, 

 and who in his dealings with scientific 

 history keeps his soul unwarped by envy, 

 hatred, or malice, personal or national, 

 every fresh accession to historic know- 

 ledge must be welcome. For every 

 new-comer of proved merit, more espe- 

 cially if that merit should have been 

 previously overlooked, he makes ready 

 room in his recognition or his reverence. 

 But no retrospect of scientific literature 

 has as yet brought to light a claim which 

 can sensibly affect the positions accorded 



