Even the possession of a considerable degree of cunning is no evidence against mental defect, but may rather be said to be a sign of it, for it shows an intelligence unable to grasp the wider relations of life, and concentrated on the gratification of petty and immediate desires. Thus it happens that the cunning of criminals is frequently associated with almost inconceivable stupidity.
Closely related to the great feeble-minded class, and from time to time falling into crime, are the inmates of workhouses, tramps, and the unemployable. The so-called "able-bodied" inmates of the workhouses are frequently found, on medical examination, to be, in more than fifty per cent cases, mentally defective, equally so whether they are men or women.
Tramps, by nature and profession, who overlap the workhouse population, and are estimated to number 20,000 to 30,000 in England and Wales, when the genuine unemployed are eliminated, are everywhere found to be a very degenerate class, among whom the most mischievous kinds of feeble-mindedness and mental perversion prevail.
Inebriates, the people who are chronically and helplessly given to drink, largely belong to the same great family, and do not so much become feeble-minded because they drink, but possess the tendency to drink because they have a strain of feeble-mindedness from birth.
Branthwaite, the chief English authority on this question, finds that of the inebriates who come to his notice, putting aside altogether the group of actually insane persons, about sixty-three per cent are mentally defective, and scarcely more than a third of the whole number of average mental capacity. It is evident that these people, even if restored to sobriety, would still retain their more or less inborn defectiveness, and would remain equally, unfit to become the parents of the coming generation.