352 Professor Tijndall [March 19, 



fusion of bis otherwise transcendent mind become conspicuous. 

 His turbid media entangle him everywhere, leading him captive and 

 committing him to almost incredible delusions. The colours of 

 tempered steel, he says, and kindred phenomena, may perhaps be 

 quite conveniently deduced from the action of turbid media. Polished 

 steel powerfully reflects light, and the colouring produced by heating 

 may be regarded as a feeble turbidity, which, acted upon by the polished 

 surface behind, produces a bright yellow. As the turbidity augments, 

 this colour becomes dense, until finally it exhibits an intense ruby- 

 red. Supposing this colour to reach its greatest proximity to dark- 

 ness, the turbidity continuing to augment as before, we shall have 

 behind the turbid medium a dark background, which appears first 

 violet, then dark blue, and finally light blue, thus completing the 

 cycle of the phenomena. The mind that could offer such an explana- 

 tion as this must be qualitatively different from that of the natural 

 philosopher. 



The words " quite conveniently deduced," which I have italicized 

 in the last paragraph, are also used by Goethe in another place. When 

 the results of his experiments on prismatic colours had to be con- 

 densed into one commanding inference, he enunciated it thus : — 

 " Und so lassen sich die Farben bei Gelegenheit der Kefraction aus 

 der Lebre von den triiben Mitteln gar bequem ableiten." This is the 

 crown of his edifice, and it seems a feeble ending to so much prepara- 

 tion. Kingsley once suggested to Lewes that Goethe might have had 

 a vague feeling that his conclusions were not sound, and that he felt 

 the jealousy incident to imperfect conviction. The ring of conscious 

 demonstration, as it is understood by the man of science, is hardly to 

 be found in the words " gar bequem ableiten." They fall flaccid upon 

 the ear in comparison with the mind-compelling Q.E.D. of Newton. 



Throughout the first 350 pages of his work, wherein be develops 

 and expounds bis own theory, Goethe restrains himself with due 

 dignity. Here and there, there is a rumble of discontent against 

 Newton, but there is no sustained ill-temper or demmciation. After, 

 however, having unfolded his own views, he comes to what he calls 

 the " unmasking of the theory of Newton." Here Goethe deliberately 

 forsakes the path of calm, objective research, and delivers himself 

 over to the guidance of his emotions. He immediately accuses 

 Newton of misusing, as an advocate, his method of exposition. He 

 goes over the propositions in Newton's optics one by one, and makes 

 even the individual words of the propositions the objects of criticism. 

 He passes on to Newton's experimental proofs, invoking, as he does 

 so, the complete attention of his readers, if they would be freed to 

 all eternity from the slavery of a doctrine which has imposed upon 

 the world for a hundred years. It might be thought that Goethe had 

 given himself but little trouble to understand the tbeorems of Newton 

 and the experiments on which they were based. But it would be 

 unjust to charge the poet with any want of diligence in this respect. 



