[38] There may be, as we before said, rare cases in which the crossing of black and white races in the first instance was not the result of primitive lust, but of profound self-abnegating affection and sympathy; in which the man or woman has deliberately selected one of the darker race for life-long companionship, and has been willing to endure all that scorn and social contumely could conflict for the sake of that companionship. Where honour and affection and life-long marriage bind a man and woman of diverse breeds, it is difficult to speak. Perhaps so mighty a love has laws of its own; and the children of such a union might be far better born and better trained than the children of average pure-breed marriages. It can only be said that such cases are so rare that practically they need hardly be considered in studying the Half-caste problems of our day. For, let it never be forgotten, the crossing of human breeds differs entirely in one all-important point from that which is artificially carried on by the breeders of domestic animals. If such breeder makes a cross, and it be found to be undesirable, and injurious to his flock, he may set to work again to eliminate it; and though every experienced breeder will confess how difficult it is to accomplish this, how again and again the strain he seeks to eliminate will crop up; nevertheless, by the free use of destruction, and by rigorously preventing from perpetuating themselves all animals which show a trace of this cross, he may, after a certain number of generations, expunge the strain. But humanity has no such power over itself. We are unable either to destroy or to prevent from breeding such varieties in our societies as may appear undesirable; and if such a variety should have physical virility and fruitfulness, society would not only be incapable of repressing it, but it might ultimately even people down all more desirable forms. Each society, as each age, has its own peculiar decalogue, applicable to its own peculiar conditions. For South Africa there are certain commandments little heard of in Europe, because the conditions of life raise no occasion for them, but which loom large in the list of social duties in this land. The first of these would appear to be--_Keep your breeds pure_! In proportion as this commandment is accepted, and its injunction carried out by our black and white races in South Africa during the next fifty years, so probably, to a large extent, will be our healthy growth and development.[39]