Since Darwin drew our attention to the struggle for existence and survival of the fittest, the perpetual strife in Nature has been clear enough. But hard, selfish, cruel, brutal though the struggle frequently is, though the strong will often trample mercilessly on the weak and let the unfit go to the wall without any consideration whatever; yet the very strongest and fittest individual could not survive for a moment by itself alone. And what is just as remarkable as the struggle between individuals is their dependence upon one another. All plants depend upon the natural elements--the soil, water, air, and light. Animals depend on plants. And many animals depend upon other animals. A forest tree in its maturity is covered with blossoms, some conspicuous, others inconspicuous to sight, but very conspicuous to smell. These blossoms, either by sight or scent, attract butterflies, bees, moths, and other insects to sip their nectar, and in so doing carry away the pollen of the flowers, and unwittingly pass it on to another flower and fertilise it. The insect thus enables the tree to procreate its species. But the butterfly, after sipping the nectar of the flower of the tree, deposits its eggs on the under surface of the leaves, and the leaves give nourishment to the caterpillars into which these eggs develop. Besides this, the flowers, having been fertilised by the insects, develop into fruits or berries containing seeds; and these fruits, berries, and seeds form food for monkeys, birds, bats, and rodents. In quarrelling for these many are dropped and form food for mice and others below. Birds, finding food so near, pair, build their nests, and bring up their young in its branches. And in addition to the birds which are attracted by the berries, fruits, and seeds, other birds which are attracted by the caterpillars come there and build their nests. Without the flowers the bees would be starved; without the bees or other insects the flowers would not be fertilised and the tree would not perpetuate itself.[*] [*] I take this illustration from Rodway's "In the Guiana Forest." It applies equally to any tropical forest. The lives of all individuals, whether plants, beasts, or men, are thus curiously interwoven with and interdependent on one another. They are also dependent upon the chemical elements in the soil and air. And even then the dependence does not cease, for they depend, too, upon the light and heat from the Sun. And the Sun itself, and this Earth as well, are subtly connected with the whole Stellar Universe.