[153] I should add that there is one obstacle, viz. expense. When the present chapter was first published in its preliminary form as an article in the _Nineteenth Century and After_ (May, 1906), Galton, always alive to everything bearing on the study of Eugenics, wrote to me that he had been impressed by the generally sympathetic reception my paper had received, and that he felt encouraged to consider whether it was possible to begin giving such certificates at once. He asked for my views, among others, as to the ground which should be covered by such certificates. The programme I set forth was somewhat extensive, as I considered that the applicant must not only bring evidence of a sound ancestry, but also submit to anthropological, psychological, and medical examination. Galton eventually came to the conclusion that the expenses involved by the scheme rendered it for the present impracticable. My opinion was, and is, that though the charge for such a certificate might in the first place be prohibitive for most people, a few persons might find it desirable to seek, and advantageous to possess, such certificates, and that it is worth while at all events to make a beginning. [154] Mannhardt, _Wald-und Feldkulte_, 1875, Vol. I, pp. 422 _et seq._ I have discussed seasonal erotic festivals in a study of "The Phenomena of Sexual Periodicity," _Studies in the Psychology of Sex_, Vol. I. [155] Thus we read in a small popular periodical: "I am prepared to back human nature against all the cranks in Christendom. Human nature will endure a faddist so long as he does not interfere with things it prizes. One of these things is the right to select its partner for life. If a man loves a girl he is not going to give her up because she happens to have an aunt in a lunatic asylum or an uncle who has epileptic fits," etc. In the same way it may be said that a man will allow nothing to interfere with his right to eat such food as he chooses, and is not going to give up a dish he likes because it happens to be peppered with arsenic. It may be so, let us grant, among savages. The growth of civilization lies in ever-extended self-control guided by foresight. [156] I have summarized some of the evidence on these points, especially that showing that sexual attraction tends to be towards like persons and not, as was formerly supposed, towards the unlike, in _Studies in the Psychology of Sex_, Vol. IV, "Sexual Selection in Man." [157] In other words, the process of tumescence is gradual and complex. See Havelock Ellis, _Studies in the Psychology of Sex_, Vol. III, "The Analysis of the Sexual Impulse."