iserable state. The checks to the population
are, of course, chiefly of the positive kind, and arise from the
diseases caused by squalid poverty. To these positive checks have of
late years been added the vice and misery of civil war, and of martial
law.

_II.--Population and the Subsistence Level_

That the checks which have been mentioned are the immediate causes of
the slow increase of population, and that these checks result
principally from an insufficiency of subsistence will be evident from
the comparative rapid increase which has invariably taken place
whenever, by some sudden enlargement in the means of subsistence, these
checks have been in any considerable degree removed. Plenty of rich land
to be had for little or nothing is so powerful a cause of population as
generally to overcome all obstacles. The abundance of cheap and
profitable land obtained by the colonists in English North America
resulted in a rapid increase of population almost without parallel in
history. Such an increase does not occur in Britain, and the reason to
be assigned is want of food. Want of food is certainly the most
efficient of the three immediate checks to population. Population soon
increases after war and disease and convulsions of nature, because the
food supply is more than adequate for the diminished numbers; but where
food is deficient no increase of population can occur.

Since the world began the causes of population and depopulation have
been probably as constant as any of the laws of nature with which we are
acquainted.

The passion between the sexes has appeared in every age to be so nearly
the same that it may always be considered in algebraic language as a
given quantity. The great law of necessity, which prevents population
from increasing in any country beyond the food which it can either
produce or acquire, is a law so obvious and evident to our
understandings that we cannot doubt it. The different modes which nature
takes to repress a redundant population do not, indeed, appear to us so
certain and regular; but though we cannot always predict the mode, we
may with certainty predict the fact. If the proportion of the births to
the deaths for a few years indicates an increase of numbers much beyond
the proportional increased or acquired food of the country, we may be
perfectly certain that, unless an emigration takes place, the deaths
will shortly exceed the births, and that the increase which has been
observe