On the other hand, the man may marry a woman in whose family consumption is unknown. The chance of their children being tuberculous will not be great; nevertheless the taint, the diathesis, will be passed on just the same, although concealed, possibly to appear at some future time. Such a marriage is in some ways more dangerous to the race, in the long run, than that of "weakness with weakness." Yet society at present certainly has no safe grounds for interference, if such a marriage is made. If the two persons come of superior stock, it seems _probable_ that the gain will outweigh the loss. In any event, it is at least to be expected that both man and woman would have a deliberate consciousness of what they are doing, and that no person with any honor would enter into a marriage, concealing a defect in his or her ancestry. Love is usually blind enough to overlook such a thing, but if it chooses not to, it ought not to be blindfolded. In short, the mating of strength with strength is certainly the ideal which society should have and which every individual should have. But human heredity is so mixed that this ideal is not always practicable; and if any two persons wish to abandon it, society is hardly justified in interfering, unless the case be so gross as those which we were discussing in the first part of this chapter. Progress in this direction is to be expected mainly from the enlightened action of the individual. Much more progress in the study of heredity must be made before advice on marriage matings can be given in any except fairly obvious cases. The most that can now be done is to urge that a full knowledge of the family history of an intended life partner be sought, to encourage the discreet inquiries and subtle guidance of parents, and to appeal to the eugenic conscience of a young man or woman. In case of doubt the advice of a competent biologist should be taken. There is a real danger that high-minded people may allow some minor physical defect to outweigh a greater mental excellence. There remains one other non-coercive method of influencing the distribution of marriage, which deserves consideration in this connection.