It is, in my judgment, both curious and interesting to study the manner in which these two illustrious men--Plato and Aristotle--dealt with the problem of population. Grave as that problem is in all times, it was peculiarly grave among the small republics of antiquity. Neither of them were disposed to ignore or overlook it: nor to impute to other causes the consequences which it produces: nor to treat as indifferent the question, whether poor couples had a greater or less family, to share subsistence already scanty for themselves. Still less were these philosophers disposed to sanction the short-sighted policy of some Hellenic statesmen, who under a mistaken view of increasing the power of the state, proclaimed encouragement and premium simply to the multiplication of male births, without any regard to the comfort and means of families. Both Plato and Aristotle saw plainly, that a married couple, by multiplying their offspring, produced serious effects not merely upon their own happiness but upon that of others besides: up to a certain limit, for good--beyond that limit, for evil. Hence they laid it down, that procreation ought to be a rational and advised act, governed by a forecast of those consequences--not a casual and unforeseen result of present impulse. The same preponderance of reason over impulse as they prescribed in other cases, they endeavoured to enforce in this. They regarded it too, not simply as a branch of prudence, but as a branch of duty; a debt due by each citizen to others and to the commonwealth. It was the main purpose of their elaborate political schemes, to produce a steady habit and course of virtue in all the citizens: and they considered every one as greatly deficient in virtue, who refused to look forward to the consequences of his own procreative acts--thereby contributing to bring upon the state an aggravated measure of poverty, which was the sure parent of discord, sedition, and crime. That the rate of total increase should not be so great as to produce these last-mentioned effects--and that the limit of virtue and prudence should be made operative on all the separate families--was in their judgment one of the most important cares of the lawgiver. We ought to disengage this general drift and purpose, common both to Plato and Aristotle, on the subject of population, from the various means--partly objectionable, partly impossible to be enforced--whereby they intended to carry the purpose into effect. [Side-note: Training of the few select philosophers to act as chiefs.]