And, indeed, the character of imperfection shows itself, as in all other human things, so also in the science of nature. From its birth among the earliest naturalists of Greece to its boasted maturity among ourselves, it counts an age of two millenniums and a half of unbroken cultivation. But now if, looking beyond the explanation of single isolated facts, we consider rather our knowledge of nature in its universal system and internal constitution, can we say that physical science has, during the time, made more than, perhaps, two steps and a half of progress? And this slow and toilsome advance which, in a certain sense, never arrives at more than “knowing in part,” is the law of every department of human science. Consequently it may be justly said of the development of man’s science, that with God a thousand years are as a day, and one day as a thousand years.[21] All knowledge drawn from the senses and experience is bound by this condition. It may, no doubt, apply immediately and principally to external experience, which is dependent on the lower and ordinary senses, whether we reckon them according to the number of their separate organs as five, or as three in compliance with a more scientific classification. But it also holds equally good of those which we pointed out and described in the last Lecture as being the four superior scientific senses, the organs of a knowledge founded on a higher and internal experience, the sense, viz., of reason, the sense of understanding, the sense for nature or fancy, and the proper sense for God, which lies in the inmost free will of man. Not merely as the faculty of suggestion [_Ahndungsvermogen_], is fancy to be regarded as the higher and internal sense for nature, or because it is from this side that the affinity of man, and of man’s soul with nature, is most distinctly revealed, but it also exhibits itself as such in the scientific apprehension of natural phenomena. That dynamical play of the inner life, that law of a living force which constitutes the essence of every phenomenon of nature, is a something so fleeting and evanescent that it can only be seized and fixed by the fancy alone, since, as is now pretty generally allowed by all profound observers of nature, in the abstract notion life eludes the grasp, and nothing remains but a dead formula.