as soon as it was perceived that the same laws which prevailed there could also claim their inviolable right here. This view of the world found its classical expression in Laplace's idea of a "world formula" by means of which every past and future event could be brought about in a strictly analytical way according to mechanical laws. For such a work, a mind was required which was far superior to the human mind, but was still essentially like it and not fundamentally different from it.
We do not ordinarily remark in how extremely high a measure this generally current view is hypothetical, even metaphysical J but are accustomed, on the other hand, to regard it as the maximum of exact formulation of actual facts. In contradiction to this it should be declared that a confirmation of the consequence that should flow out of this theory—that all the non-mechanical processes, like heat, light, electricity, magnetism, and chemism, are really mechanical—can not be reached in any single case. It has never been possible in any one of these instances so to account for the actual conditions by a corresponding mechanical system that there should be no remainder.
Mechanical interpretations, it is true, have been given with more or less considerable success to individual phenomena; but when the attempt has been made to account for all the facts in any given field by means of a mechanical conception, it has always and without exception come to pass that an irreconcilable contradiction appeared at some point, between the actual state of the phenomena and that which the mechanical conception would lead us to expect. Such contradictions might remain hidden for a long time; but the history of science teaches us that they will inevitably sooner or later come to light; and that all that we can say with full certainty of such mechanical conceptions or analogies as are usually called mechanical theories of the phenomena in question is that they will at any rate fill the gap for the present.
The history of optical theories affords a conspicuous example of these conditions. So long as all optics included nothing more than the phenomena of reflection and refraction, an interpretation was possible under the mechanical scheme proposed by Newton, according to which light consists of small particles which, thrown out straightwise by shining bodies, behaved according to the laws of moving and perfectly elastic masses. That another mechanical view, the undulatory theory proposed by Huygens and Euler, accomplished quite as much, might make the exclusive validity of the former theory doubtful, but could not deprive it of its predominance. But when the phenomena of polarization and interference were discovered, Newton's mechanical conception was found wholly inadequate, and the other, the undulatory theory,
