The fundamental fact on which Mr. Darwin’s theory rests is the “struggle for existence.”  Life is not something to be idly enjoyed, but a prize to be won; the world is not a play-ground, but an arena.  And the severity of the struggle can scarcely be overrated.  Only one or two of a host of runners reach the goal, the others die along the course.  Concerning this there can be no doubt, and there is little room for difference of interpretation.

The struggle may take the form of a literal battle between two individuals, or of the individual with inclemency of climate or other destructive agents.  More usually it is a competition, no more noticeable and no less real than that between merchants or manufacturers in the same line of trade.

The weeds in our gardens compete with the flowers for food, light, and place, and crowd them out unless prevented by man.  And when the weeds alone remain, they crowd on each other until only a few of the hardiest and most vigorous survive.  And flowers, by their nectar, color, and odor, compete for the visits of insects, which insure cross-fertilization.  And fruits are frequently or usually the inducements by which plants compete for the aid of animals in the dissemination of their seeds.  So there is everywhere competition and struggle; many fail and perish, few succeed and survive.

In a foot-race it is often very difficult to name the winner.  Muscle alone does not win, not even good heart and lungs.  Good judgment, patience, coolness, courage, many mental and moral qualities, are essential to the successful athlete.  So in the struggle for life.  The race is not always to the swift, nor the battle to the strong.

The total of “points” which wins this “grand prize” is the aggregate of many items, some of which appear to us very insignificant.  Hence, when we ask, “Who will survive?” the answer is necessarily vague.  Mr. Darwin’s answer is, Those best conformed to their environment; and Mr. Spencer’s statement of the survival of the fittest means the same thing.

The judges who pronounce and execute the verdict of death, or award the prize of life, are the forces and conditions of environment.  We have already considered the meaning of this word.  Many of its forces and conditions are still unknown, or but very imperfectly understood.  But known or unknown, visible or invisible, the result of their united action is the extinction or degradation of these individuals which deviate from certain fairly well-marked lines of development.  We must keep clearly before our minds the fact that the world of living beings makes up by far the most important part of the environment of any individual plant or animal.  Two plants may be equally well suited to the soil and climate of any region; but if one have a scanty development of root or leaf, or is for any reason more liable to attacks from insects or germs, other things being equal, it will in time be crowded out by its competitor.  Worms are eaten by lower vertebrates, and these by higher.  An animal’s environment, like that of a merchant or manufacturer, is very largely a matter of the ability and methods of its competitors.  And man, compelled to live in society, makes that part of the environment by which he is most largely moulded.