[26] The term "feeble-minded" may be used generally to cover all degrees of mental weakness. In speaking a little more precisely, however, we have to recognize three main degrees of congenital mental weakness: _feeble-mindedness_, in which with care and supervision it is possible to work and earn a livelihood; _imbecility_, in which the subject is barely able to look after himself, and sometimes only has enough intelligence to be mischievous (the moral imbecile); and _idiocy_, the lowest depth of all, in which the subject has no intelligence and no ability to look after himself. More elaborate classifications are sometimes proposed. The method of Binet and Simon renders possible a fairly exact measurement of feeble-mindedness. [27] Mott (_Archives of Neurology and Psychiatry_, Vol. V, 1911) accepts the view that in some cases feeble-mindedness is simply a form of congenital syphilis, but he points out that feeble-mindedness abounds in many rural districts where syphilis, as well as alcoholism, is very rare, and concludes by emphasizing the influence of heredity; the prevalence of feeble-mindedness in these rural districts is thus due to the fact that the mentally and physically fit have emigrated to the great industrial centres, leaving the unfit to procreate the race. [28] "Whether germinal variations," remarked Dr. R.J. Ryle at a Conference on Feeble-mindedness (_British Medical Journal_, October 3, 1911), "be expressed by cleft palate, cataract, or cerebral deficiency of the pyramidal cells in the brain cortex, they may be produced, and, when once produced, they are reproduced as readily as the perfected structure of the face or eye or brain, if the gametes which contain these potentialities unite to form the ovum. But Nature is not only the producer. Given a fair field and no favour, natural selection would leave no problem of the unfit to perplex the mind of man who looks before and after. This we know cannot be, and we know, too, that we have no longer the excuse of ignorance to cover the neglect of the new duties which belong to the present epoch of civilization. We know now that we have to deal with a growing group in our community who demand permanent care and control as well for their own sakes as for the welfare of the community. All are now agreed on the general principle of segregation, but it is true that something more than this should be forthcoming. The difficulties of theory are clearing up as our wider view obtains a firmer grasp of our material, but the difficulties of practice are still before us." These remarks correspond with the general results reached by the Royal Commission on the Feeble-minded, which issued its voluminous facts and conclusions in 1908. [29] See, for instance, A.F. Tredgold, _Mental Deficiency_, 1908.