Page:Two Lectures on the Checks to Population.pdf/20

14 the rate of progression, yet prescribe no bounds to the ultimate accumulation of population; while those of the second class, i.e. those which determine the third rate of increase, not only lessen the rate of progression, but also conﬁne the amount of ultimate accumulation.

The remark, therefore, which I made on Mr. Malthus' enumeration of the checks amounts to this, that they comprise the whole difference between the first and third rates, or between the ideal rate of duplication in ten years and the actual rate, and not that part only of the difference which depends on a scarcity of the means of subsistence.

Assume the circumstances of a nation to admit of a certain rate of advance in its means of subsistence; then its population will increase at the same rate, and the whole difference between the first rate of increase and the third will be a given quantity. The two classes of checks therefore, viz those independent of, and those generated by,