THE JURISPRUDENCE OF INSANITY. 45 



doctors, lawyers, clergymen, merchants, as well as ordinary day 

 labourers, go on each with his ^jroper work while yet a victim of 

 delusional insanity, it is evident that at any moment, and from any 

 quarter, a specimen case may present itself for the consideration of 

 the Courts. 



The class of cases which I propose to discuss in this paper is com- 

 prised very generally under the head of the ordinary term " insanity," 

 though the legal term is "unsoundness of mind," and the questions 

 which Jurisprudence has in view are : — 



1. When is any given person to be considered as insane. 



2. What degree of responsibility or capacity is he fixed or gifted 

 with . 



The law sets out with the assumption that all men are sane, but 

 nevertheless it recognizes the fact that some ai-e insane ; just as the 

 law recognizes the existence of crime, although acting ordinarily on 

 the presumption that every person accused is innocent. The law as- 

 sumes the more noble, more perfect state of humanity. 



The gradation from sanity to insanity, as from health to disease, 

 or light to darkness, may be slow or instantaneous, as those versed 

 in such matters may speculate. The law when called upon has to 

 say which of the two states exists. The twilight stage — part 

 sane and part insane, weak-minded, balancing between capacity and 

 incapacity — is a condition that calls for the greatest vigilance at its 

 hands, especially as regards property and contracts generally. 



" Sanity," says a great English lawyer, " exists when the brain 

 and the nervous system are in such condition that the mental func- 

 tions of feeling and knowing, emotion and willing, can be performed 

 in their regular and usual manner." 



"Insanity," says the same authority, " means that state in which 

 one or more of the above-mentioned mental functions is performed in 

 an abnormal manner, or not performed at all, by reason of some dis- 

 ease of the brain or nervous system." 



The result of this is stated by the same author to be knowledge 

 that an act is wrong and the power to abstain from doing it. Tbis 

 is the test in criminal matters. A similar rule ajDplies in civil cases. 



How is it to be determined that any given person has knowledge 

 of right and wrong, and a will to do the one and shun the other 1 



