It is probably true that in the course of the biological history of the earth, whole species have been rendered extinct by parasites, or by changing outward conditions. But this has been the exception, and not the rule. The chestnut blight now seems to threaten the very existence of this species of tree in this country, but I think the chances are that this fungus will meet with some natural check. In early summer comes the June drop of apples. The trees start with more fruit than they can carry, and if they are in vigorous health, they will drop the surplus. It is a striking illustration of Nature’s methods. The tree does its own thinning. But if not at the top of its condition, it fails to do this. It takes health and strength simply to let go; only a living tree drops its fruit or its leaves; only a growing man drops his outgrown opinions. If we put ourselves in the place of the dropped apples, we must look upon our fate as unmixed evil. If we put ourselves in the place of the tree and of the apples that remain on it, the June drop would appear an unmixed good--finer fruit, and a healthier, longer-lived tree results. Nature does not work so much to specific as to universal ends. The individual may go, but the type must remain. The ranks may be decimated, but the army and its cause must triumph. Life in all its forms is a warfare only in the sense that it is a struggle with its outward conditions, in which, other things being equal, the strongest force prevails. Small and weak forms prevail also, because the competing forms are small and weak, or because at the feast of life there is a place for the small and weak also. But lion against lion, man against man, mouse against mouse, the strongest will, in the end, be the victor. Man’s effort is to save waste, to reduce friction, to take short cuts, to make smooth the way, to seize the advantage, to economize time, but the physical forces know none of these things.