Mr. Darwin himself, who is constantly supposed to have upheld, or even to have demonstrated, the fact of spontaneous generation, is amongst the strongest witnesses against it. He was indeed disposed to believe that the living will some day be found to be producible from the lifeless, the ground of his expectation being the "Law of Continuity,"[90] or the assumption that from the beginning of nature to the end one only kind of law uniformly operates, namely the same as we now experience. But this is to assume the whole question at issue, for unless it can be shewn that there has been spontaneous generation, we cannot be assured that there is such a Law of Continuity. And despite his expectation Darwin always denied that the origin of life has been--sometimes even that it can be--explained. Thus he wrote on various occasions: It is mere rubbish thinking at present of the origin of life; one might as well think of the origin of matter.[91] As for myself I cannot believe in spontaneous generation, and though I expect that at some future time the principle of life will be rendered intelligible, at present it seems to me beyond the confines of Science.[92] No evidence worth anything has as yet, in my opinion, been advanced in favour of a living being, being developed from inorganic matter.[93] Here we may conveniently pause and take stock of our results. On the one hand, we are bidden in the name of Science to learn the past from the present, and the present from observation and experiment alone. On the other, we are invited to believe in an occurrence which observation and experiment negative in the present, on the ground that the circumstances must once have been entirely different from any with which we are acquainted. Obviously, the real motive of belief is that naïvely expressed by Professor Haeckel, who tells us that spontaneous generation is proved by the doctrine of Evolution;[94] which then in its turn is proved by spontaneous generation. Two points must however be noticed in which it is attempted to find present evidence in favour of spontaneous generation.