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that is, the theoretical excess of the births above the deaths, may be reduced to the dimensions of the increase actually possible, in two ways, namely, either by a diminution in the births, or an increase in the deaths. Mr. Malthus therefore distinguishes the checks into two principal classes, the preventive, which restrain the number of the actual births, and prevent its being as great as the theoretical number: and the positive, which swell the number of the deaths, and increase them beyond the proportion due to the natural law of mortality in the human species.
There is reason to believe, as I intimated in a previous Lecture, that the poverty and hard living, which in many cases operate to the destruction of life, have in other cases the effect of diminishing fecundity. So far as they produce this latter effect they are preventive checks. Promiscuous intercourse, beyond a certain degree, prevents the birth of children, and therefore belongs to the same class. But the most important branch of the preventive check consists in, what is termed by Mr. Malthus, moral restraint. For an explanation of its nature, I will read his own description of it.
