The existing races constitute separate branches of one or many primitive stocks. These stocks have now vanished. They are not known in historical times at all, and we cannot form even the most general idea of their qualities. They differed from each other in the shape and proportion of the limbs, the structure of the skull, the internal conformation of the body, the nature of the capillary system, the colour of the skin, and the like; and they never succeeded in losing their characteristic features except under the powerful influence of the crossing of blood. This permanence of racial qualities is quite sufficient to generate the radical unlikeness and inequality that exists between the different branches, to raise them to the dignity of natural laws, and to justify the same distinctions being drawn with regard to the physiological life of nations, as I shall show, later, to be applicable to their moral life. Owing to my respect for a scientific authority which I cannot overthrow, and, still more, for a religious interpretation that I could not venture to attack, I must resign myself to leaving on one side the grave doubts that are always oppressing me as to the question of original unity; and I will now try to discover as far as I can, with the resources that are still left to me, the probable causes of these ultimate physiological differences. As no one will venture to deny, there broods over this grave question a mysterious darkness, big with causes that are at the same time physical and supernatural. In the inmost recesses of the obscurity that shrouds the problem, reign the causes which have their ultimate home in the mind of God; the human spirit feels their presence without divining their nature, and shrinks back in awful reverence. It is probable that the earthly agents to whom we look for the key of the secret are themselves but instruments and petty springs in the great machine. The origins of all things, of all events and movements, are not infinitely small, as we are often pleased to say, but on the contrary so vast, so immeasurable by the poor foot-rule of man’s intelligence, that while we may perhaps have some vague suspicion of their existence, we can never hope to lay hands on them or attain to any sure discovery of their nature. Just as in an iron chain that is meant to lift up a great weight it frequently happens that the link nearest the object is the smallest, so the proximate cause may often seem insignificant; and if we merely consider it in isolation, we tend to forget the long series that has gone before. This alone gives it meaning, but this, in all its strength and might, derives from something that human eye has never seen. We must not therefore, like the fool in the old adage, wonder at the power of the roseleaf to make the water overflow; we should rather think that the reason of the accident lay in the depths of the water that filled the vessel to overflowing. Let us yield all respect to the primal and