As for the case of the Habsburgs in particular, he concludes:— “The Habsburgs of Spain have long since been swept off the stage of history, disappearing in sterility or insanity. The Habsburgs of Austria, numerous though the representatives of the House are at the present time, will end by disappearing in their turn as an historic family, if they persist in their errors,—that is to say, in their marriages with blood relations.” It is a new way of looking at an old problem,—a new thought suggested by the latest of the sciences; and it opens the door to reflections of great and urgent moment to many other royal houses besides that of Habsburg. In a general way, it has long been held to be almost as improper for Kings and Queens to marry their subjects as for angels to marry the daughters of men. A purer and bluer blood ran in their veins than in the veins of their subjects; and to adulterate that blue blood with red blood was to degrade it. They must, therefore, seek their brides and bridegrooms within the magic circle. Kings must marry Queens, and Princes must marry Princesses; and the distinctive exclusiveness of reigning houses must be maintained by a succession of unions between cousins. That view of the matter has continued to prevail in royal circles—and also in high political and diplomatic circles—long after the students of heredity have established conclusions unfavourable to such courses. The arguments can hardly have failed to reach the ears of those whom they concerned; and the feeling—tacit, if not avowed—has presumably been that Kings, and Queens, and Princes and Princesses are so great and good and glorious that the laws of Nature do not apply to them. But that is not the case. Science shows that Kings cannot override the laws of Nature even in the countries in which they are permitted to override the laws of the land; that the price which Nature exacts for exclusiveness is degeneracy; that hardly any royal family anywhere has failed to pay that price; that the percentage of insanity has, through the ages, been higher among hereditary rulers whose blue blood has thus been protected from admixture than in any other class of the community; and that the sound physiological instinct is that on which King Cophetua acted in the legend, when the bare-footed beggar-maid appeared before him:— As shines the moon in clouded skies, She in her poor attire was seen; One praised her ankles, one her eyes, One her dark hair and lovesome mien. So sweet a face, such angel grace, In all that land had never been: Cophetua swore a royal oath: “This beggar maid shall be my queen.”