of members of 112 different families, of which only 58 were in existence in a century and a half afterward.
If we consider special cases of noted men, the great generals of the world, the commanding statesmen, the distinguished scientists, the celebrated authors—all, in fact, who have become distinguished for superior mental ability—an almost universal result appears: they have either left no descendants, or their families were very small. And, for that matter, we need but to look at evidences everywhere surrounding us. We think it will be found to be a general rule that persons constantly exercised in mental labor have few or no children; those of less active minds have larger families; while the largest families belong to those who do not trouble themselves to think at all.
There is abundant reason to believe, then, that such a physiological check to population really exists; and, in its operation, it is not difficult to perceive a rich promise for the future of the human race. For it is in no sense, in its superior phase, a starvation check. Nor does it need any of the violent repression of natural desires exercised in the prudential check. At first sight, it appears as if its tendency must be to constantly place the cultured at a disadvantage in numbers as compared with the dull and ignorant. But this disadvantage is more than counterbalanced by the progress of education and the brain-incitements of modern civilization. Thus, the class of brain-workers is being continually recruited, despite its lack of fecundity, and we can see indications of an immense future augmentation of this class of the population at the expense of the unthinking, and consequently of a new barrier to the progress of population, whose efficacy is now but beginning to appear.
It is a process which must in time do away with the "starvation check" to population, and replace it with a new and far more desirable limiting principle. For when nerve-energy largely replaces muscular energy, and advanced education greatly increases the percentage of the cultured, there may be a corresponding decrease in the birth-rate, through the operation of the causes just considered. And, as human want decreases and comfort advances, the developed needs of mankind must extend the prudential check on early marriage, which is so active now in the middle classes. In this another limiting force will be brought to bear upon the increase of population.
Thus, as the sum of human wealth increases, through the exercise of intelligence in industrial operations, it will necessarily be divided among a population not increasing in an equal ratio. The average wealth of all classes of the community must increase in consequence, the necessary amount of active muscular labor be reduced, and more time be given for rest, enjoyment, or indulgence in mental culture.
The more rapidly that wealth accumulates in proportion to population, and, the more vigorously that culture forces its way downward through the community, the greater must be the effect of the pruden-
