cultivators to employ more labour upon their land, to
turn up fresh soil, and to manure and improve more completely what is
already in tillage, till ultimately the means of subsistence become in
the same proportion to the population as at the period from which we
set out. The situation of the labourer being then again tolerably
comfortable, the restraints to population are in some degree loosened,
and the same retrograde and progressive movements with respect to
happiness are repeated.

This sort of oscillation will not be remarked by superficial observers,
and it may be difficult even for the most penetrating mind to calculate
its periods. Yet that in all old states some such vibration does exist,
though from various transverse causes, in a much less marked, and in a
much more irregular manner than I have described it, no reflecting man
who considers the subject deeply can well doubt.

Many reasons occur why this oscillation has been less obvious, and less
decidedly confirmed by experience, than might naturally be expected.

One principal reason is that the histories of mankind that we possess
are histories only of the higher classes. We have but few accounts that
can be depended upon of the manners and customs of that part of mankind
where these retrograde and progressive movements chiefly take place. A
satisfactory history of this kind, on one people, and of one period,
would require the constant and minute attention of an observing mind
during a long life. Some of the objects of inquiry would be, in what
proportion to the number of adults was the number of marriages, to what
extent vicious customs prevailed in consequence of the restraints upon
matrimony, what was the comparative mortality among the children of the
most distressed part of the community and those who lived rather more
at their ease, what were the variations in the real price of labour,
and what were the observable differences in the state of the lower
classes of society with respect to ease and happiness, at different
times during a certain period.

Such a history would tend greatly to elucidate the manner in which the
constant check upon population acts and would probably prove the
existence of the retrograde and progressive movements that have been
mentioned, though the times of their vibrations must necessarily be
rendered irregular from the operation of many interrupting causes, such
as the introduction or failure of certain manufactures, a gr