"There may be more truth in the adventurous pangenesis of Darwin — whom Tyndall calls a "soaring speculator" — than in the cautious, line-bound hypothesis of the latter; who, in common with other thinkers of his class, surrounds his imagination "by the firm frontiers of reason." The theory of a microscopic germ which contains in itself "a world of minor germs," soars in one sense at least into the infinite. It oversteps the world of matter and begins unconsciously busying itself in the world of spirit. If we accept Darwin's theory of the development of species, we find that his starting point is placed in front of an open door. We are at liberty with him, to either remain within, or cross the threshold, beyond which lies the limitless and the incomprehensible, or rather the Unutterable."