To Malthus, vice and misery, as checks to population, were an evil greatly to be deplored in civilized man, and not only did he declare that moral restraint obtained as a check, but he also declared it a virtue to be advocated and encouraged in the interest of society, as well as of the individual.

His moral restraint was delayed marriage with continence.  He trusted to the moral force of the sexual passion in a continent man to stimulate to work, to thrift, to marriage; to work and save so that he may enter the marriage state with a reasonable prospect of being able to support a wife and family.

Malthus never anticipated the changes and developments of recent years.  He advised moral restraint as a preventive measure in the hope that vice and misery, as checks would be superseded, and that no more would be born into the world than there was ample food to supply.  He believed that moral restraint was the check of civilized man, and as civilization proceeded, this check would replace the others, and prevent absolutely the population pressing upon the limits of subsistence.

He saw in moral restraint only self-denial, constant continence, and entertained not a doubt, that the generative instinct would be cheated of its natural fruit.  The passion for marriage is so strong (thought Malthus) that there is no fear for the race; it cannot be over-controlled.

The gratification of the sexual instinct, and procreation were the same thing in the mind of Malthus.

But this is not so.

A physiological law makes it possible, in a large proportion of strictly normal women, for union to take place without fertilisation.  If it were possible to maintain an intermittent restraint in strict conformity with this law, it would control considerably the population of the world.

It is easier to practice intermittent than to practice constant restraint.

It is just here that Malthus failed to anticipate the future.  Malthus believed that “moral restraint” would lessen the marriage rate, but would have no direct effect on the fecundity of marriage.

A man would not put upon himself the self-denial and restraint, which abstinence from marriage implied, for a longer period than he could help.

The greater the national prosperity, therefore, the higher the birth-rate.  But prosperity keeps well in advance of the birth-rate; in other words, population, though it still tends to, does not actually press upon the food supply.

If the moral restraint of Malthus be extended so as to include intermittent moral restraint within the marriage bond, then, under one or other, or all of his three checks, vice, misery, and moral restraint, will be found the explanation of the remarkable demographic phenomena of recent years.

Misery will cover deaths from starvation and poverty, the limitation of births from abortion due to hardship, from deaths due to improper food, clothing, and housing; and emigration to avoid hardship.