But as we look still further into the matter, our mood is changed once more. We find that this hideous hatred and strife, this wholesale famine and death, furnish the indispensable conditions for the evolution of higher and higher types of life. Nay more, but for the pitiless destruction of all individuals that fall short of a certain degree of fitness to the circumstances of life into which they are born, the type would inevitably degenerate, the life would become lower and meaner in kind. Increase in richness, variety, complexity of life is gained only by the selection of variations above or beyond a certain mean, and the prompt execution of a death sentence upon all the rest. The principle of natural selection is in one respect intensely Calvinistic; it elects the one and damns the ninety and nine. In these processes of Nature there is nothing that savours of communistic equality; but "to him that hath shall be given, and from him that hath not shall be taken away even that which he hath." Through this selection of a favoured few, a higher type of life--or at all events a type in which there is more life--is attained in many cases, but not always. Evolution and progress are not synonymous terms. The survival of the fittest is not always a survival of the best or of the most highly organized. The environment is sometimes such that increase of fitness means degeneration of type, and the animal and vegetable worlds show many instances of degeneration. One brilliant instance is that which has preserved the clue to the remote ancestry of the vertebrate type. The molluscoid ascidian, rooted polyp-like on the sea beach in shallow water, has an embryonic history which shows that its ancestors had once seen better days, when they darted to and fro, fishlike, through the waves, with the prophecy of a vertebrate skeleton within them. This is a case of marked degeneration. More often survival of the fittest simply preserves the type unchanged through long periods of time. But now and then under favourable circumstances it raises the type. At all events, whenever the type is raised, it is through survival of the fittest, implying destruction of all save the fittest.