mountable difficulties arise. But the very existence of the laws themselves appears more and more problematical. Lotze himself already suspected a fallacy in them. He awaited, before putting faith in them, 'sound waves which should give to the eye the sensation of light, or luminous vibrations which should give to the ear a sound.'[1] The truth is that all the facts alleged can be brought back to a single type: the one stimulus capable of producing different sensations, the multiple stimuli capable of inducing the same sensation, are either an electric current or a mechanical cause capable of determining in the organ a modification of electrical equilibrium. Now we may well ask whether the electrical stimulus does not include different components, answering objectively to sensations of different kinds, and whether the office of each sense is not merely to extract from the whole the component that concerns it. We should then have, indeed, the same stimuli giving the same sensations, and different stimuli provoking different sensations. To speak more precisely, it is difficult to admit, for instance, that applying an electrical stimulus to the tongue would not occasion chemical changes; and these changes are what, in all cases, we term tastes. On the other hand, while the physicist has been able to identify light with an electro-magnetic disturbance, we may say, inversely, that what he
- ↑ Lotze, Metaphysic, Oxford, 1887, vol. ii, p. 206.
