shall we perceive how both are governed by the influence of thoughts which, springing up at first we know not how or whence in a few superior minds, gradually spread till they have leavened the whole inert lump of a community or of mankind. The origin of such mental variations, with all their far-reaching train of social consequences, is just as obscure as is the origin of those physical variations on which, if biologists are right, depends the evolution of species, and with it the possibility of progress. Perhaps the same unknown cause which determines the one set of variations gives rise to the other also. We cannot tell. All we can say is that on the whole in the conflict of competing forces, whether physical or mental, the strongest at last prevails, the fittest survives. In the mental sphere the struggle for existence is not less fierce and internecine than in the physical, but in the end the better ideas, which we call the truth, carry the day. The clamorous opposition with which at their first appearance they are regularly greeted, whenever they conflict with old prejudices, may retard but cannot prevent their final victory. [Sidenote: The tombs of the prophets.] It is the practice of the mob first to stone and then to erect useless memorials to their greatest benefactors. All who set themselves to replace ancient error and superstition by truth and reason must lay their account with brickbats in their life and a marble monument after death. [Sidenote: Superstition the creed of the laggards in the march of intellect.] I have been led into making these remarks by the wish to explain why it is that superstitions of all sorts, political, moral, and religious, survive among peoples who have the opportunity of knowing better. The reason is that the better ideas, which are constantly forming in the upper stratum, have not yet filtered through from the highest to the lowest minds. Such a filtration is generally slow, and by the time that the new notions have penetrated to the bottom, if indeed they ever get there, they are often already obsolete and superseded by others at the top. Hence it is that if we could open the heads and read the thoughts of two men of the same generation and country but at opposite ends of the intellectual scale, we should probably find their minds as {169} different as if the two belonged to different species. Mankind, as it has been well said, advances in _échelons_; that is, the columns march not abreast of each other but in a straggling line, all lagging in various degrees behind the leader. The image well describes the difference not only between peoples, but between individuals of the same people and the same generation. Just as one nation is continually outstripping some of its contemporaries, so within the same nation some men are constantly outpacing their fellows, and the foremost in the race are those who have thrown off the load of superstition which still burdens the backs