It will however be replied that the phenomena of living beings are far more complex than the phenomena of Astronomy or Physics--and that is the reason why exact science makes so little way with them. Though man knows many million times more about the habits of his fellow-men than about the habits of the stars, yet the former subject is so many million times more complicated than the latter that all his additional knowledge does not avail him. This is the plea. Yet it does not hold water. It is an entire assumption to say that the phenomena of Astronomy are less complicated than the phenomena of vitality. A moment's thought will show that the phenomena of Astronomy are in reality infinitely complex. Take the movement of the moon: even with our present acquaintance with that subject we know that it has some relation to the position and mass of the earth, including its ocean tides; also to the position and mass of the sun; also to the position and mass of every one of the planets; also of the comets, numerous and unknown as they are; also the meteoric rings; and finally of all the stars! The problem, as everyone knows, is absolutely insoluble even for the shortest period; but when the element of Time enters in, and we consider that to do anything like justice to the problem in an astronomical sense we should have to solve it for at least a million years--during which interval the earth, sun, and other bodies concerned would themselves have been changing their relative positions, it becomes obvious that the whole question is infinitely complex--and yet this is only a small fragment of Astronomy. To debate, therefore, whether the infinite complexity of the movements of the stars is greater or less than the infinite complexity of the phenomena of life, is like debating the precedence of the three persons of the Trinity, or whether the Holy Ghost was begotten or proceeding: we are talking about things which we do not understand. Nature is one; she is not, we may guess, less profound and wonderful in one department than another; but from the fact that we live under certain conditions and limitations we see most deeply into that portion which is, as it were, on the same level with us. In humanity we look her in the face; there our glance pierces, and we see that she is profound and wonderful beyond all imagination; what we learn there is the most valuable that we can learn. In the regions where Science rejoices to disport itself we see only the skirts of her garments, so to speak, and though we measure them never so precisely, we still see them and nothing more.