To another of those questions the judges answered, that a person partially insane was to be treated _as if the facts were just what he imagined them to be_, as if his delusions were realities. His conduct was to be judged by his own premises. This was accepted as law by England, and is the law now both there and here, and, I suppose, throughout the civilized world. Now, these are exactly the conclusions about an insane man's responsibility which we had arrived at before, reasoning from psychological and ethical first principles. It is therefore for the consequences of an insane delusion only that a man is not responsible before the inward court of conscience and the outward courts of justice. But the case is altogether different when the error is not the result of insane delusion. When a man, sane or partially insane, has reasoned himself into a false opinion or conviction, not the result of his insanity, that the crime he is going to commit is justifiable, such conviction being his own free act does not exempt him from punishment. This was the precise point on which turned the celebrated case of Guiteau, the murderer of President Garfield. His trial before the Supreme Court, District of Columbia, December, 1882, was one of the most interesting that have ever occurred in this country or elsewhere in connection with the plea of insanity. In his very able and exhaustive instructions to the jury on that occasion, Judge Cox states the rule that is to guide the jury in these words: "It has been argued with great force on the part of the defendant that there are a great many things in his conduct which could never be expected of a sane man, and which are only explainable on the theory of insanity. The very extravagance of his expectations in connection with this deed--that he would be protected by the men he was to benefit, would be applauded by the whole country when his motives were made known--has been dwelt upon as the strongest evidence of unsoundness. Whether this and other strange things in his career are really indicative of partial insanity, or can be accounted for by ignorance of men, exaggerated egotism, or perverted moral sense, might be a question of difficulty. And difficulties of this kind you might find very perplexing if you were compelled to determine the question of insanity generally, without any rule for your guidance. "But the only safe rule for you is to direct your reflections to the one question which is the test of criminal responsibility, and which has been so often repeated to you, viz., whether, whatever may have been the prisoner's singularities and eccentricities, he possessed the mental capacity, at the time the act was committed, to know that it was wrong, or was deprived of that capacity by mental disease."