In this matter we may neglect altogether the so-called æsthetic factor, the stimulus of beauty. For does it not frequently happen that one man is completely captivated by a particular woman and raves about her beauty, whilst another, who is not the sexual complement of the woman in question, cannot imagine what his friend sees in her to admire. Without discussing the laws of æsthetics or attempting to gather together examples of relative values, it may readily be admitted that a man may consider a woman beautiful who, from the æsthetic standpoint, is not merely indifferent but actually ugly, that in fact pure æsthetics deal not with absolute beauty, but merely with conceptions of beauty from which the sexual factor has been eliminated. I have myself worked out the law in, at the lowest, many hundred cases, and I have found that the exceptions were only apparent. Almost every couple one meets in the street furnishes a new proof. The exceptions were specially instructive, as they not only suggested but led to the investigation of other laws of sexuality. I myself made special investigations in the following way. I obtained a set of photographs of æsthetically beautiful women of blameless character, each of which was a good example of some definite proportion of femininity, and I asked a number of my friends to inspect these and select the most beautiful. The selection made was invariably that which I had predicted. With other male friends, who knew on what I was engaged, I set about in another fashion. They provided me with photographs from amongst which I was to choose the one I should expect them to think most beautiful. Here, too, I was uniformly successful. With others, I was able to describe most accurately their ideal of the opposite sex, independently of any suggestions unconsciously given by them, often in minuter detail than they had realised. Sometimes, too, I was able to point out to them, for the first time, the qualities that repelled them in individuals of the opposite sex, although for the most part men realise more readily the characters that repel them than the characters that attract them. I believe that with a little practice any one could readily acquire and exercise this art on any circle of friends. A knowledge of other laws of sexual affinity would be of great importance. A number of special constants might be taken as tests of the existence of complementary individuals. For instance, the law might be caricatured so as to require that the sum of the length of the hairs of any two perfect lovers should always be the same. But, as I have already shown in chapter ii., this result is not to be expected, because all the organs of the same body do not necessarily possess the same degree of maleness or femaleness. Such heuristic rules would soon multiply and bring the whole subject into ridicule, and I shall therefore abstain from further suggestions of the kind.