4. But, it will be said, sickly and consumptive subjects, and still more those who have any tendency to madness, may well be excused from having children; so too may they be excused whose poverty cannot keep a family; excused too is the inveterate drunkard, and all habitual criminals, by the principle of heredity, lest they transmit to posterity an evil bodily predisposition; but the healthy and the virtuous, men sound of mind and limb, of life unspotted, and in circumstances easy, the flower of the race,--none of these surely should omit to raise up others to wear his lineaments: we want such men multiplied. I answer, on natural grounds alone: You may counsel, but you cannot compel, either by positive law or ethical precept, any man or woman to seek to have children. You surely will not breed men by selection, like cattle, as Plato proposed. The union of the sexes, especially the married union, is an act to be of all others the most entirely free, spontaneous, uncommanded, and unconstrained. It should be a union of intense mutual love. But a man may not meet with any woman that he can love with passion; or, meeting such, he may not be able to win her. Nor, considering the indeterminateness of points of health, capacity, and character, could any certain list be drawn up of persons bound to have issue. Thus the utmost that can be argued is a counsel in this direction, a counsel that mankind ordinarily are ready enough to comply with. But if any one of seeming aptitude excuses himself on the score of finding no partner to his liking, or of a desire to travel, or of study, or still more, of devotion--and why should not a man, ever of natural piety, go out into solitude, like St. Antony, to hold communion with his Maker?--all these excuses must be taken. It is lawful then in the state of mere nature, upon any one of many sufficient grounds, to stand aside and relinquish to your neighbour the privilege and responsibility of giving increase to the human family. 5. But if it is no one individual's duty to propagate his kind, how is it that we have laid down that there is such a duty? For the duty is incumbent upon them that alone can do it, and it can only be done by individuals. The answer rests on a distinction between _proximate_ and _remote_ duty. The propagation of the race is the remote duty of every individual, but at present the proximate, duty of none. A _remote_ duty is a duty not now pressing but which would have to be performed in a certain contingency, which contingency happening, the duty becomes _proximate_. If there appeared a danger of our race dying out, the survivors would be beholden, especially those in power, to take steps for its continuance. Rewards might then be held out, like the _jus trium liberorum_ instituted at Rome by Augustus; and if necessary, penalties inflicted on celibacy. In this one extreme case the matrimonial union might be made matter of legal constraint. But when will such constraint become necessary?