Aristotle has not fully considered all that Plato says, when he blames him for inconsistency in proposing to keep properties equal, without taking pains to impose and maintain a constant limit on offspring in families. [Greek: A)/topon de\ kai\ to\ ta\s ktê/seis i)sa/zonta] (Plato) [Greek: to\ peri\ to\ plê=thos tô=n politô=n mê\ kataskeua/zein, a)ll' a)phei=nai tê\n teknopoii+/an a)o/riston], &c. (Aristot. Polit. ii. 6, p. 1265, a. fin.) What Plato really directs is stated in my text and in my note immediately preceding.] [Footnote 170: Aristotel. Politic. vii. 16, p. 1334, b. 39. [Greek: ei)/per ou)=n a)p' a)rchê=s to\n nomothe/tên o(ra=|n dei=, o(/pôs be/ltista ta\ sô/mata ge/nêtai tô=n trephome/nôn, prô=ton me\n e)pimelête/on peri\ tê\n su/zeuxin, po/te kai\ poi/ous tina\s o)/ntas chrê\ poiei=sthoi pro\s a)llê/lous tê\n gamikê\n o(mili/an], &c. He names thirty-seven as the age proper for a man, eighteen for a woman, to marry. At the age of fifty-five a man becomes unfit to procreate for the public, and none of his children are to appear ([Greek: a)phei=sthai tê=s ei)s to\ phanero\n gennê/seôs], vii. 16, p. 1335, b. 36).] The paramount necessity of limiting the number of children born in each family, here enforced by Plato and Aristotle, rests upon that great social fact which Malthus so instructively expounded at the close of the last century. Malthus, enquiring specially into the law of population, showed upon what conditions the increase of population depends, and what were the causes constantly at work to hold it back--checks to population. He ranged these causes under three different heads, though the two last are multiform in detail. 1. Moral or prudential restraint--the preventive check. 2. Vice, and 3. Misery--the two positive checks. He farther showed that though the aggregate repressive effect of these three causes is infallible and inevitable, determined by the circumstances of each given society--yet that mankind might exercise an option through which of the three the check should be applied: that the effect of the two last causes was in inverse proportion to that of the first--in other words, that the less there was of prudential restraint limiting the number of births, the more there must be of vice or misery, under some of their thousand forms, to shorten the lives of many of the children born--and _é converso_, the more there was of prudential restraint, the less would be the operation of the other checks tending to shorten life. [Side-note: Plato and Aristotle saw the same law as Malthus, but arranged the facts under a different point of view.]