This is a more prominent element as we approach the more human side (if I may so call it) of Political Economy. Consider, for example, the doctrine which made so profound an impression upon the old school--Malthus's theory of population. It was summed up in the famous--though admittedly inaccurate--phrase, that population had a tendency to increase in a geometrical ratio, while the means of subsistence increased only in an arithmetical ratio. The food available for each unit would therefore diminish as the population increased. The so-called law obviously states only a possibility. It describes a "tendency," or, in other words, only describes what would happen under certain, admittedly variable, conditions. It showed how, in a limited area and with the efficiency of industry remaining unaltered, the necessary limits upon the numbers of the population would come into play. If, then, the law were taken, or in so far as it was taken, to assert that, in point of fact, the population must always be increasing in civilised countries to the stage at which the lowest class would be at starvation level, it was certainly erroneous. There are cases in which statesmen are alarmed by the failure of population to show its old elasticity, and beginning to revert to the view that an increased rate is desirable. It cannot be said to be even necessarily true that in all cases an increased population implies, of necessity, increased difficulty of support. There are countries which are inadequately peopled, and where greater numbers would be able to support themselves more efficiently because they could adopt a more elaborate organisation. Nor can it be said with certainty that some pressure may not, within limits, be favourable to ultimate progress by stimulating the energies of the people. In a purely stationary state people might be too content with a certain stage of comfort to develop their resources and attain a permanently higher stage. Whatever the importance of such qualifications of the principle, there is a most important conclusion to be drawn. Malthus or his more rigid followers summed up their teaching by one practical moral. The essential condition of progress was, according to them, the discouragement of early marriages. If, they held, people could only be persuaded not to produce families until they had an adequate prospect of supporting their families, everything would go right. We shall not, I imagine, be inclined to dispute the proposition, that a certain degree of prudence and foresight is a quality of enormous value; and that such a quality will manifest itself by greater caution in taking the most important step in life. What such reasoners do not appear to have appreciated was, the immense complexity and difficulty of the demand which they were making. They seem to have fancied that it was possible simply to add another clause--the clause "Thou shalt not marry"--to the accepted code of morals; and that, as soon as the evil