Is it then, or is it not, conceivable, that under the circumstances of the time and country, a tribe or clan of 5,000 persons may have increased in 430 years to one of two millions? Here it has to be remembered that there were two modes whereby they might increase, one that of ordinary natural increase, the other by augmentation of the number of their retainers. The natural tendency of population has been shown by Mr. Malthus, to be to double itself, if unchecked, every 25 years.[78] The Israelites, having the land of Goshen, a large fertile territory, capable of supporting a population of several millions, assigned them, would be in a position where the checks on the natural tendency, especially at first, would be very slight. Now, according to the estimate of Mr. Malthus, a body of 5,000 persons increasing without check, would have become more than two millions at the end of 225 years; a body of 267 persons would have exceeded the same amount at the close of 325 years; and a body even of seventy persons would have done the same at the expiration of 375 years; so that, except for the operation of artificial checks, the family of Jacob, had it really consisted of seventy persons only, would have become one of above two millions fifty-five years before the time of the exodus. But, no doubt, as the increase took place, the artificial checks, which keep down the natural tendency of population, began to operate, and the result was, that if the original immigrants were, as I have supposed, about 5,000, the actual rate of increase had been a doubling, not once each twenty-five years, but once each forty-eight years, or not very much beyond the rate which prevails in our own country at the present time. If we add to this the consideration that the Israelites, being in a very flourishing condition during the earlier portion of their sojourn in Egypt, would naturally augment, by purchase, the number of their households, and might even receive, by agreement, whole tribes into their body, we shall not be surprised that at the end of the 430 years, the clan had grown to be a nation of two million souls.