In Massachusetts, Connecticut, and Ohio, efforts have been made, by correspondence with physicians and town officers, to obtain data from which an approximate estimate might be attained. These efforts, though not so satisfactory as could be desired, are yet sufficient to authorize the conclusion that there are in those three States (and probably the same figures would hold good for the rest of the Union) about one fifth of one per cent. of the population who are idiots of low grade, and about the same number who are of weak and imbecile intellect. This would give us in the United States about fifty-two thousand idiots, and as many more imbeciles. At the lowest estimate, the cost of supporting this vast army of the unfortunate, beyond the trifling sum which a few of them may be able to earn, is more than ten millions of dollars per annum. Nor is this all, or even the worst feature of their case. The greater part of them are without sense of shame, without any notions of chastity or decency, and so weak in moral sense as to be the ready tools and dupes of artful villains, and often themselves exhibit a perverseness and malignity of character which render them dangerous members of society. Their influence for evil, direct and indirect, no man can estimate. The chaplains and other officers of our State prisons and penitentiaries will testify that a large proportion of the inmates of those establishments, though not idiots, are weak-minded and imbecile; and it by no means a rare circumstance to find persons, who should properly be under treatment as idiots, suffering the doom of the felon. Under these circumstances, the question, What can be done with this unfortunate and helpless class? becomes one of great importance. A careful examination of the institutions for their training in this country and Europe, and an extended inquiry into their present condition when not under instruction, have enabled us to arrive at the following conclusions. There is very little hope of any considerable permanent improvement of the idiot, if not placed under training before his sixteenth year. His habits may, indeed, be somewhat amended, and the mind temporarily roused; but this improvement will seldom continue after he is removed from the institution. The existence of severe epilepsy, or other profound disease, is a serious bar to success.