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eye of the philosopher, and we are at liberty to reason respecting the quantities placed on each side of this line in the same manner as if its position were actually ascertained.
We shall thus have a third rate of increase, viz. a theoretical rate, which might be expected to have a real existence, were not only food always abundant, but also all wars, all diseases, and other causes in any way tending to diminish fecundity, or to extinguish human life before the completion of the natural term of longevity, to be utterly removed. The three rates will then stand as follows:
First, we shall have a theoretical rate, derived from the supposition of the absence, not only of a scarcity of food, but also of all other causes whatever, which tend to diminish fecundity, or prematurely to weaken or destroy the human frame. Let us assume this to be such as would double population in ten years.
Secondly, we shall have another theoretical rate, derived from the supposition of the absence only of a scarcity of food, and not of the other causes of retardation unconnected with this scarcity. This is not, like the other, merely an imaginary
