According to English law a man is irresponsibly insane, when he has “such 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.” This definition is very incomplete and covers only the most obvious forms of insanity; perhaps in the great majority of cases there is no “defect of reason” nor “disease of mind” in the proper sense of these terms, but only a disturbance of the emotions or perversion of the will originating in physical disorder. Besides, it is undeniable that animal intelligence is capable of distinguishing between right and wrong and of comprehending what is punishable and what is not punishable. In general when a dog does wrong, he knows that he is doing wrong; and a monkey often takes delight in doing what is wrong simply because he knows it is wrong. If a monkey gets angry and kills a child, he obeys the same vicious propensity that impels a brutal man to commit murder. There is no greater “defect of reason” in one case than in the other. Why then should the monkey be summarily shot or knocked on the head, and the man arrested, tried, convicted and hanged by the constituted authorities? Simply because such a public prosecution and execution would not exert any influence whatever in preventing infanticide on the part of other monkeys; if it could be shown that a formal trial of the monkey would produce this salutary effect, then it certainly ought not to be omitted. The recent attempt to modify the English law so as to render all “certifiably insane” persons irresponsible for their actions, would result in the abolition of all punishment for crime, since many physicians regard every criminal as insane and would not hesitate to certify their opinion to the proper tribunal.