PHYSIOLOGY. 145 



is, in this respect, in the marking of relations and in joining or 

 separating ideas, a considerable difference among men in the 

 state of health. The objects, indeed, about which men are con- 

 versant, are for the most part the same ; and there is so much 

 similarity in the operations of the human mind, that the same 

 relations of ideas are marked, so that there is a sameness of 

 judgment established among different men. We are according- 

 ly most secure in ascertaining an error of judgment when there 

 is a considerable deviation from the common sense of mankind ; 

 and such a deviation may then be considered as a disease. But 

 still there is a certain latitude admitted in judgment. Men dif- 

 fer greatly from one another, without any of them being reckon- 

 ed delirious. In accounting a man delirious, therefore, we must 

 farther observe that he is deviating from his ordinary judg- 

 ment, and from his usual train of thinking. This subject 

 might be prosecuted with some curiosity : thus men speak of a 

 weakness of mind without delirium ; they explain errors in 

 judgment by calling them mistakes and blunders ; they distin- 

 guish between the wrong-headed and those who are wrong in 

 the head ; they point out differences between whim, folly, and 

 madness, &c. These distinctions might have some curiosity 

 and use ; but they are matters of too much subtlety, and it is 

 enough to leave them to common apprehension. 



" The third manner in which delirium appears is in an er- 

 roneous will, that is, when emotions are not suited or propor- 

 tioned to their objects ; when they arise in a manner which is 

 either uncommon to mankind in general or unusual to the per- 

 son who is their present subject. With regard to this third 

 kind, we may observe, that emotions and passions not propor- 

 tioned to their objects, will readily follow when errors of 

 judgment, the second state of delirium, exist. I have taken 

 pains to show that the mind may be in different tones in 

 this respect: that this tone may appear in gaiety and sad- 

 ness, in irascibility and timidity, and that the causes of mad- 

 ness more frequently depend upon this tone of mind than 

 even upon the errors of sense or judgment ; and it is sufficiently 

 evident, that irregular emotions or passions seldom occur, except 

 when a particular tone of mind is joined to the false imagination 

 and to the error in judgment. Thus, Dr. Sydenham observes, 

 VOL. i. K 



