But while affirming that the disease usually arises in the body, and even frequently in parts far removed from the brain, we must not deny nor ignore the fact that intellectual and protracted worry, or sudden and violent grief, can also be the direct cause of disturbance in the brain. For the brain is the organ not of the imagination alone, which is put to an unhealthy strain by excessive mental labor, but probably also of the passions, whose emotions when excessive may cause even permanent lesion. Hence mental insanity may and does often arise from ill-subdued passions. The knowledge of all this may enable the physician to remove the exciting cause or to mitigate its influence; it may also aid expert witnesses, judges, lawyers, and jurymen to ascertain the main fact with which the courts are concerned, namely, the presence or absence of mental insanity at the time of a given civil or criminal action. V. Supposing then that, in the case before the court, the fact of insanity is established, the next question of Jurisprudence to determine is this: How far and why ought such unsoundness of mind to exclude responsibility for deliberate acts? It is a clear principle of reason that no man can justly be blamed or punished for doing what he cannot help doing; now an insane man cannot help judging wrong at times; he cannot then justly be blamed for acting on his mistaken judgments. If he invincibly judges an act to be morally good whereas it is morally bad, no matter how criminal the act may be--say the killing of his own father or child--if he commits the deed with the full conviction that he is doing right, he cannot be blamed or punished for committing that awful crime. The principle then is clear that an insane man is not to be held responsible to God or man for his insane acts. For the root and reason of our responsibility for an act lies in the fact that we do the deed of our own free choice; knowing its moral nature, being masters of our own free will, so that, if we do one act in preference to another, we wilfully take upon ourselves the consequences of this preference as far as we can know or suspect them. If we do what we are firmly convinced is right, just, worthy of a man, we deserve praise; if we do what we are convinced or suspect is wrong, unjust, unworthy of a man, we deserve blame and punishment. But an insane man may do the most unjust act, and yet feel invincibly convinced that it is just; he cannot then be held responsible for doing it, because the root of responsibility is then wanting.