536 PRACTICE OF PHYSIC. 



food ought, in moderate cases of melancholia, to be used with 

 some caution. 



Though exercise, as a tonic power, is not proper either in 

 hypochondriasis or melancholia, yet with respect to its effects 

 upon the mind, it may be extremely useful in both ; and in 

 melancholia it is to be employed in the same manner that I 

 have advised above in the case of hypochondriasis. 



MDXCVIII. Having now delivered my doctrine with re- 

 spect to the chief forms of insanity, L should in the next place 

 proceed to consider the other genera of Amentia and Oneiro- 

 dynia, which, in the Nosology, I have arranged under the order 

 of Vesaniae : but as I cannot pretend to throw much light upon 

 these subjects, and as they are seldom the objects of practice, I 

 think it allowable for me to pass them over at present ; and the 

 particular circumstances of this work in some measure require 

 that I should do so. 



" Many may think the genus Oneirodynia altogether un- 

 necessary, as being no disease, and indeed it is seldom the 

 object of practice. This is true, but still it is a disease, and 

 the second species of it, the O. gravans, EphialleS) or Night- 

 mare, has been sometimes an object of practice. 



" I think every instance of dreaming a disease, as perfect 

 sleep suspends every part of mental operations, and in most 

 instances dreams manifestly depend upon some fault in the 

 system, or some stimulus externally applied. This must also 

 account for dreaming being generally delirious, and therefore 

 depending on inequality of excitement. There may be ex- 

 ceptions alleged of coherent dreams ; but even these, as always 

 partial, shew the same inequality. This subject of dreaming 

 might be pursued as a theory with some curiosity, but with 

 a view to practice we have nothing to say respecting it ; it is 

 to be prevented rather than cured, and the several causes that 

 have a tendency to produce it are therefore to be avoided. 



" The Nightmare has been more commonly considered as a 

 disease requiring treatment, and justly so, as it is often a pre- 

 lude to the Comata, and occurs especially in persons disposed 

 to these. 

 5 " The theory of this is not quite agreed upon ; for, while 



