[17] Archbold‘s _Criminal Cases_. Lord Hale, who first pointed out the distinction to be drawn between total and partial insanity, offered the following as the best test he could suggest: “Such a person, as labouring under melancholy distempers, hath yet as great understanding as ordinarily a child of fourteen years hath, is such a person as can be guilty of felony.” (On this subject, see R. _v_. Ld. Ferrers, 19 St. Tr. 333; R. _v_. Arnold, 16 St. Tr. 764, &c.) To excuse a man from punishment on the ground of insanity, it appears that it must be distinctly proved that he was not capable of distinguishing right from wrong, and that he did not know, at the time of committing the crime, that the offence was against the laws of _God_ and _nature_ (R. _v_. Offord, 5 C. & P. 186). I shall here quote from Macdonald‘s _Criminal Law of Scotland_: “Insanity or idiocy exempts from prosecution. But there must be an alienation of reason such as misleads the judgment, so that the person does not know ‘the nature of the quality of the act’ he is doing, or if he does know it, that he does not know he is doing what is wrong. If there be this alienation, as connected with the act committed, he is not liable to punishment, though his conduct may be otherwise rational. For example, if he kill another when under an insane delusion as to the conduct and character of the person--_e.g._ believing that he is about to murder him, or is an evil spirit,--then it matters not that he has a general notion of right and wrong. For, in such a case, ‘as well might he be utterly ignorant of the quality of murder.’ He does the deed, knowing murder to be wrong, but his delusion makes him believe he is acting in self-defence, or against a spirit. Nor does it alter the effect of the fact of insanity at the time, that the person afterwards recovers.... But the alienation of reason must be substantial. Oddness or eccentricity, however marked, or even weakness of mind, will not avail as a defence. Even monomania may be insufficient as a defence, where the delusion and the crime committed have no connection, or where the person, though having delusions, was yet aware that what he did was illegal.” Mere moral insanity--where the intellectual faculties are sound, and the person knows what he is doing, and that he is doing wrong, but has no control over himself, and acts under an uncontrollable impulse--does not render him irresponsible (R. _v_. Burton, 3 F. & F. 772). Some medical writers contend that there are two forms of insanity--moral and intellectual. The law only recognises the latter, owing probably to the difficulty of distinguishing between so-called moral insanity and moral depravity. Taylor says: “Further, until medical men can produce a clear and well-defined distinction between moral depravity and moral insanity, such a doctrine, employed as it has been for the exculpation of persons charged with crime, should be rejected as inadmissible.”