Child labour, which once may, industrially speaking, have been an economical method of consuming the available human material, is no longer compatible with the highest industrial efficiency, even apart from any question of hardship or deterioration incident to an excessive or abusive recourse to child labour; it is incompatible with the community’s material interests. Therefore the business community--the body of businessmen at large--for whose behoof the industries of the country are carried on, have a direct interest not only in extending the age of exemption from industrial employment but also in procuring an adequate schooling of the incoming generation of workmen. The business community is evidently coming to appreciate this state of the case, at least in some degree, as is evidenced by their inclination to favour instruction in the “practical” branches in the public schools, at the public expense, as well as by the wide-reaching movement that aims to equip private and state schools that shall prepare the youth for work in the various lines of industrial employment. [141] _Cf._, _e. g._, Adam Smith’s reflections on the uses of an accurate watch, _Theory of the Moral Sentiments_, part iv, ch. 2. [142] On the other hand the aphorism often cited, that “Necessity is the Mother of Invention,” appears to be nothing better than a fragment of uncritical rationalism. It offers a rationalised, _ex post facto_ account of changes that take place, and reflects that ancient preconception by help of which the spokesmen of edification were enabled to interpret all change as an improvement due to the achievement of some definitely foreknown end. It appears also to be consistently untrue, except so far as “invention” is to be taken as a euphemistic synonym for “prevarication.” Doubtless, the felt need of ways and means has brought on many changes in technology, but doubtless also the ulterior consequences of any one of the greater mechanical inventions have in the main been neither foreseen nor intended in the designing of them. The more serious consequences, especially such as have an institutional bearing, have been enforced by the inventions rather than designed by the inventors. [143] See pp. 18–21, above. [144] Cf., however, what has been said above (pp. 21–23) of the variability and adaptability of a hybrid population and the possible selective establishment of a hybrid type more suitable to current conditions of life than any one of the racial stocks out of which the hybrid population is made up.