Unfortunately, that which had at first been merely a means to an end presently became an end in itself. Losing sight of his idealisms, nineteenth-century man evolved a thoroughly materialistic philosophy. The upshot was a warped, one-sided development which quickly revealed its unsoundness. The fact that man was much less culpable for his errors than many moralists aver is quite beside the point, so far as consequences are concerned. Nature takes no excuses. She demands results, and when these are not forthcoming she inexorably inflicts her penalties. As the nineteenth century drew toward its close the symptoms of a profound _malaise_ appeared on every side. Even those most fundamental of all factors, the vitality and quality of the race, were not immune. Vital statistics began to display features highly disquieting to thoughtful minds. The most striking of these phenomena was the declining birth-rate which affected nearly all the white nations toward the close of the nineteenth century and which in France resulted in a virtually stationary population. Of course the mere fact of a lessened birth-rate, taken by itself, is not the unmixed evil which many persons assume. Man's potential reproductive capacity, like that of all other species, is very great. In fact, the whole course of biological progress has been marked by a steady checking of that reproductive exuberance which ran riot at the beginning of life on earth. As Havelock Ellis well says: "Of one minute organism it is estimated that, if its reproduction were not checked by death or destruction, in thirty days it would form a mass a million times larger than the sun. The conger-eel lays 15,000,000 eggs, and if they all grew up, and reproduced themselves on the same scale, in two years the whole sea would become a wriggling mass of fish. As we approach the higher forms of life reproduction gradually dies down. The animals nearest to man produce few offspring, but they surround them with parental care, until they are able to lead independent lives with a fair chance of surviving. The whole process may be regarded as a mechanism for slowly subordinating quantity to quality, and so promoting the evolution of life to ever higher stages."[97]