From the higher standpoint of general culture the difficult question forces itself on us: What is the real value of the idea of evolution in the whole realm of science? We are bound to answer that it varies considerably. The facts of the evolution of the individual, or of ontogeny, were easy to observe and grasp: the evolution of the crust of the earth and of the mountains in geology seemed to have an equally sound empirical foundation; the physical evolution of the universe seemed to be established by mathematical speculation. There was no longer any serious question of _creation_, in the literal sense, of the deliberate action of a personal Creator, in these great provinces. But this made people cling to the idea more than ever in regard to the origin of the countless species of animals and plants, and especially the creation of man. This transcendental problem seemed to be entirely beyond the range of natural development; and the same was thought of the question of the nature and origin of the soul, the mystic entity that was appropriated by metaphysical speculation as its subject. Charles Darwin suddenly brought a clear light into this dark chaos of contradictory notions in 1859. His epoch-making work, _The Origin of Species_, proved convincingly that this historical process is not a supernatural mystery, but a physiological phenomenon; and that the preservation of improved races in the struggle for life had produced, by a natural evolution, the whole wondrous world of organic life. To-day, when evolution is almost universally recognised in biology, when thousands of anatomic and physiological works are based on it every year, the new generation can hardly form an idea of the violent resistance that was offered to Darwin's theory and the impassioned struggles it provoked. In the first place, the Churches at once raised a vigorous protest; they rightly regarded their new antagonist as the deadly enemy of the legend of creation, and saw the very foundations of their creed threatened. The Churches found a powerful ally in the dualistic metaphysics that still claims to represent the real "idealist philosophy" at most universities. But most dangerous of all to the young theory was the violent resistance it met almost everywhere in its own province of empirical science. The prevailing belief in the fixity and the independent creation of the various species was much more seriously menaced by Darwin's theory than it had been by Lamarck's transformism. Lamarck had said substantially the same thing fifty years before, but had failed to convince through the lack of effective evidence. Many scientists, some of great distinction, opposed Darwin because either they had not an adequate acquaintance with the whole field of biology, or it seemed to them that his bold speculation advanced too far from the secure base of experience.