PHYSIOLOGY. 219 



therefore, will apply very extensively ; but perhaps it may not 

 seem to be very readily applicable to that great variety which 

 would appear to take place in the human constitution. 



With a view, therefore, to attempt some explanation of this 

 variety, we shall remark, in the first place, that it may in some 

 measure depend upon the two temperaments, which we have 

 supposed chiefly to prevail, being seldom perfectly formed ; or, 

 in other words, upon the particular state of the circumstances 

 in which they consist being seldom found in the most complete 

 degree. For example, it is seldom that in the sanguine the 

 simple solid is the most lax, or in the melancholic the most 

 rigid that is compatible with health. There is reason to sup- 

 pose, that from the medium state of density and firmness in the 

 solid, there may be various intermediate degrees between the 

 most lax upon the one hand, and the most rigid upon the other; 

 and supposing that with each of these intermediate degrees, 

 there is united a corresponding state of the nervous power, there 

 may then be so many intermediate and seemingly varying tem- 

 peraments, neither completely sanguine nor melancholic, though 

 always approaching to the one or the other. This may, in 

 some measure, explain the varieties in the temperaments of 

 men, but it may be justly doubted if it will account for the 

 whole. 



It will therefore be proper, in the second place, to observe, 

 that it is doubtful if the circumstances of the economy are al- 

 ways in the same proportion to one another that has been above 

 supposed. For example, we have supposed that the density and 

 the mobility of the nervous power are always in a certain pro- 

 portion to one another : but this is not very certainly the case ; 

 and if we may suppose, as seems to be allowable, that in two 

 persons, the density being equal, the mobility may be greater in 

 the one than in the other ; so that if this should happen, it 

 will be obvious that it might give a more exquisite formation of 

 the sanguine, or a more moderate state of the melancholic tem- 

 perament. In this way it is possible, that with a certain degree 

 of density greater than usual in the sanguine, there may be a 

 mobility greater than in proportion to this ; we shall then have a 

 middle temperament between the sanguine and the melancholic, 

 and perhaps what the ancients meant to denote by the title of 



