1. Shall it be applied before trial? Here the answer is prompt. It is the right of every person whom the law presumes innocent, as is the case with all before trial, to be kept free from the touch or contamination of those who may be felons. I well remember the indignation of the late William Ellery Channing at an incident which occurred in our streets, where a stranger who had fallen under suspicion, but who proved to be innocent, was marched from the jail handcuffed, in company with a hardened offender. He held it the duty of the State to prevent such outrage. The principle of justice and humanity which led him to his conclusion in this case requires the _absolute separation_ of all prisoners before trial. 2. A more perplexing problem arises with regard to convicts for short terms. Here, it would seem, the principle of _absolute separation_ ought to prevail. 3. It is a question of greater doubt how to treat juvenile offenders. When we observe the admirable success of the House of Reformation at South Boston, and of the Penal Colony at Mettray, in France, both conducted on the social principle, we may well hesitate; though, on the other hand, the marked success of the institution of La Roquette, at Paris, under peculiar difficulties, shows that the principle of _absolute separation_ may be applied even to this class of offenders. Here certainly is a question worthy of consideration. 4. Shall the Separate System be applied in any case to women? The authority of Mrs. Fry, in England, who at first disapproved the system, but at the close of her valuable life approved it, even for her own sex, also that of Mademoiselle Josephine Mallet, in France, who has declared herself warmly for this system, entitle this question to careful attention. 5. And, lastly, shall the Separate System be applied to convicts for long terms? This is, indeed, the crucial question, involving statistics of health and insanity, and many other considerations, on which much light is shed by the experience of Europe, as well as our own country, and also by writings of eminent characters devoted to this subject. Here we may well hesitate, and open our minds to influences from all quarters. * * * * * The way is now prepared to consider whether our Society, in unfolding what may be called the science of Prison Discipline, has treated the Pennsylvania System, involving the several questions already stated, with candor and justice. The question is not whether this system is preferable in all cases to every other, or whether there is any other preferable to this, but simply, Has our Society been candid and just? An examination of its course furnishes an easy answer.