one form:  If species were not supernaturally created, we cannot understand the facts x, or y, or z; we cannot understand the structure of animals or plants, unless we suppose they were contrived for special ends; we cannot understand the structure of the eye, except by supposing it to have been made to see with; we cannot understand instincts, unless we suppose animals to have been miraculously endowed with them.

As a question of dialectics, it must be admitted that this sort of reasoning is not very formidable to those who are not to be frightened by consequences.  It is an argumentum ad ignorantiam—­take this explanation or be ignorant.  But suppose we prefer to admit our ignorance rather than adopt a hypothesis at variance with all the teachings of Nature?  Or, suppose for a moment we admit the explanation, and then seriously ask ourselves how much the wiser are we; what does the explanation explain?  Is it any more than a grandiloquent way of announcing the fact, that we really know nothing about the matter?  A phenomenon is explained when it is shown to be a case of some general law of Nature; but the supernatural interposition of the Creator can, by the nature of the case, exemplify no law, and if species have really arisen in this way, it is absurd to attempt to discuss their origin.

Or, lastly, let us ask ourselves whether any amount of evidence which the nature of our faculties permits us to attain, can justify us in asserting that any phaenomenon is out of the reach of natural causation.  To this end it is obviously necessary that we should know all the consequences to which all possible combinations, continued through unlimited time, can give rise.  If we knew these, and found none competent to originate species, we should have good ground for denying their origin by natural causation.  Till we know them, any hypothesis is better than one which involves us in such miserable presumption.

But the hypothesis of special creation is not only a mere specious mask for our ignorance; its existence in Biology marks the youth and imperfection of the science.  For what is the history of every science but the history of the elimination of the notion of creative, or other interferences, with the natural order of the phaenomena which are the subject-matter of that science?  When Astronomy was young “the morning stars sang together for joy,” and the planets were guided in their courses by celestial hands.  Now, the harmony of the stars has resolved itself into gravitation according to the inverse squares of the distances, and the orbits of the planets are deducible from the laws of the forces which allow a schoolboy’s stone to break a window.  The lightning was the angel of the Lord; but it has pleased Providence, in these modern times, that science should make it the humble messenger of man, and we know that every flash that shimmers about the horizon on a summer’s evening is determined by ascertainable conditions, and that its direction and brightness might, if our knowledge of these were great enough, have been calculated.