But while it is good that a man should be able to do this often, it is not good to try to do it always. The very restraint which adds to a man's strength up to a point, taxes his strength when carried beyond it. It is my belief that just sufficient restraint to carry him through the ebb-tides of his wife's sex-rhythm is usually the right amount to give the best strength, vigour, and joy to a man if both are normal people. If the wife has, as I think the majority of healthy, well-fed young women will be found to have, a fortnightly consciousness or unconscious _potentiality_ of desire, then the two should find a perfect mutual adjustment in having fortnightly unions; for this need not be confined to only a single union on such occasion. Many men, who can well practise restraint for twelve or fourteen days, will find that one union only will not then thoroughly satisfy them; and if they have the good fortune to have healthy wives, they will find that the latter, too, have the desire for several unions in the course of a day or two. If the wave-crests facing page 32 are studied, it will be seen that they spread over two or three days and show several small minor crests. This is what happens when a woman is thoroughly well and vital; her desire recurs during a day or two, sometimes even every few hours if it does not, and sometimes even when it does, receive satisfaction. Expressed in general terms (which, of course, will not fit everybody) my view may be formulated thus: The mutually best regulation of intercourse in marriage is to have three or four days of repeated unions, followed by about ten days without any unions at all, unless some strong external stimulus has stirred a mutual desire. I have been interested to discover that the people known to me who have accidentally fixed upon this arrangement of their lives are _happy_: and it should be noted that it fits in with the charts I give which represent the normal, spontaneous feeling of so many women.