For example, if under the influence of his delusion he supposes another man to be in the act of attempting to take away his life, and kills the man, as he supposes in self-defence, he would be exempt from punishment.

If his delusion was that the deceased had inflicted a serious injury to his character and fortune, and he killed him in revenge for such supposed injury, he would be liable to punishment.
Question 2.--"What are the proper questions to be submitted to the jury when a person, afflicted with insane delusions respecting one or more particular subjects or persons, is charged with the commission of a crime (murder, for instance), and insanity is set up as a defence?
Question 3.--"In what terms ought the question to be left to the jury as to the prisoner's state of mind when the act was committed?
Answers 2 and 3.--"As these two questions appear to us to be more conveniently answered together, we submit our opinion to be that the jurors ought to be told, in all cases, that every man is presumed to be sane, and to possess a sufficient degree of reason to be responsible for his crimes, until the contrary be proved to their satisfaction; and that, to establish a defence on the ground of insanity it must be clearly proved that at the time of committing the act the accused was laboring under such a defect of reason, from disease of the mind, as not to know the nature and quality of the act he was doing, or, if he did know it, that he did not know he was doing what was wrong." (The remainder of the answer goes on to discuss the usual way the question is put to the jury.) Now, with that commendable reverence for judicial utterance which is so characteristic of the English nation, and is so conspicuously absent in our own country, it was assumed until recently that this solemn pronunciamento was the last word on the question of criminal responsibility and settled the matter once and forever.

Barristers and legislators did not trouble themselves particularly over the fact that in 1843 the study of mental disease was in its infancy, and judges, including those of England, probably knew even less about the subject than they do now.

In 1843 it was supposed that insanity, save of the sort that was obviously maniacal, necessitated "delusions," and unless a man had these delusions no one regarded him as insane.

In the words of a certain well-known judge: "The true criterion, the true test of the absence or presence of insanity, I take to be the absence or presence of what, used in a certain sense of it, is comprisable in a single term, namely, delusion....