But Ellis’ faulty inference is still based upon a sound observation, to wit, that the sort of man capable of transmitting high talents to a son is ordinarily a man who does not have a son at all, at least in wedlock, until he has advanced into middle life. The reasons which impel him to yield even then are somewhat obscure, but two or three of them, perhaps, may be vaguely discerned. One lies in the fact that every man, whether of the first-class or of any other class, tends to decline in mental agility as he grows older, though in the actual range and profundity of his intelligence he may keep on improving until he collapses into senility. Obviously, it is mere agility of mind, and not profundity, that is of most value and effect in so tricky and deceptive a combat as the duel of sex. The aging man, with his agility gradually withering, is thus confronted by women in whom it still luxuriates as a function of their relative youth. Not only do women of his own age aspire to ensnare him, but also women of all ages back to adolescence. Hence his average or typical opponent tends to be progressively younger and younger than he is, and in the end the mere advantage of her youth may be sufficient to tip over his tottering defences. This, I take it, is why oldish men are so often intrigued by girls in their teens. It is not that age calls maudlinly to youth, as the poets would have it; it is that age is no match for youth, especially when age is male and youth is female. The case of the late Henrik Ibsen was typical. At forty Ibsen was a sedate family man, and it is doubtful that he ever so much as glanced at a woman; all his thoughts were upon the composition of “The League of Youth,” his first social drama. At fifty he was almost as preoccupied; “A Doll’s House” was then hatching. But at sixty, with his best work all done and his decline begun, he succumbed preposterously to a flirtatious damsel of eighteen, and thereafter, until actual insanity released him, he mooned like a provincial actor in a sentimental melodrama. Had it not been, indeed, for the fact that he was already married, and to a very sensible wife, he would have run off with this flapper, and so made himself publicly ridiculous.