The greatest, vastest, and most difficult of all cosmic problems is that of the origin and development of the world—the “question of creation,” in a word. Even to the solution of this most difficult world-riddle the nineteenth century has contributed more than all its predecessors; in a certain sense, indeed, it has found the solution. We have at least attained to a clear view of the fact that all the partial questions of creation are indivisibly connected, that they represent one single, comprehensive “cosmic problem,” and that the key to this problem is found in the one magic word—evolution. The great questions of the creation of man, the creation of the animals and plants, the creation of the earth and the sun, etc., are all parts of the general question, What is the origin of the whole world?