One of the favorite methods of Mr. Spencer consists in arraying difficulties for the believers in special creations, which, he argues, can not be encountered by their hypothesis, and then arguing that there are no difficulties in the way of the hypothesis of evolution. His position shall be stated with all the strength that he gives to it, and with all the care that I can bestow upon its treatment. He puts the argument thus: In the animal kingdom individuals come into being by a process of generation--that is to say, they arise out of other individuals of the same species. If we contemplate the individuals of any species, we find an evolution repeated in every one of them by a uniform process of development, which, in a short space of time, produces a series of astonishing changes. The seed becomes a tree, and the tree differs from the seed immeasurably in bulk, structure, color, form, specific gravity, and chemical composition; so that no visible resemblance can be pointed out between them. The small, semi-transparent gelatinous spherule constituting the human ovum becomes the newly-born child; and this human infant "is so complex in its structure that a cyclopædia is needed to describe its constituent parts. The germinal vesicle is so simple that it may be defined in a line. Nevertheless, a few months suffice to develop the one out of the other, and that, too, by a series of modifications so small that were the embryo examined, at successive minutes, even a microscope would with difficulty disclose any sensible changes. Aided by such facts, the conception of general evolution may be rendered as definite a conception as any of our complex conceptions can be rendered. If, instead of the successive minutes of a child's fœtal life, we take successive generations of creatures, if we regard the successive generations as differing from each other no more than the fœtus did in successive minutes, our imaginations must indeed be feeble if we fail to realize in thought the evolution of the most complex organism out of the simplest. If a single cell, under appropriate conditions, becomes a man in the space of a few years, there can surely be no difficulty in understanding how, under appropriate conditions, a cell may, in the course of untold millions of years, give origin to the human race."[72]