458 INTRODUCTORY LECTURES. 



tended to in forming our characters ; but I am satisfied that 

 though this internal seat is, with much propriety, added to the 

 history of the disease, it is better not taken into the specific char- 

 acter, as it never is directly evident, and only such marks ought 

 to be employed as are evident. Lrinnoeus in the characters of his 

 class Dolorosi, always employs the internal seat ; and he is suf- 

 ficiently cautious with regard to some of them, as when he says, 

 ' Gastrica, ventriculi dolor epigastrii; Colica, intestini dolor 

 umbilicalis ;' but the definitions of Hysteralgia and Nephritica, 

 by ( uteri dolor, 1 and < renis dolor," are inadmissible, because it is 

 not always certain when the uterus and when the kidneys are 

 the seat of pain. 



These are a few rules with respect to what diseases should be 

 comprehended in our system, or what diseases we should at- 

 tempt to characterize. I must mention another, however, which 

 may appear sufficiently obvious, but which it is not unnecessary 

 to advert to, viz. that every disease which earn be distinguished 

 from another, ought to be taken into our system. It has been 

 long objected to the Botanists, that they have loaded us with a 

 number of useless plants ; for of the ten thousand of which 

 they possess the knowledge we do not know any use for more 

 than two hundred. This objection may be still farther urged 

 against those who have described insects. But those who make 

 such objections have not been aware of the purpose of method 

 in any part of science. Supposing that we wish to know about 

 three hundred plants, we cannot do this completely till the 

 whole ten thousand have been also characterized : for we shall 

 not be able to separate and distinguish the former, till the whole 

 are compared. In order, therefore, to render our arrangement 

 perfect and complete, we require to distinguish not only what is 

 absolutely necessary and useful, but even that which may hap- 

 pen to be of no use. The Nosologists who have gone before me, 

 accordingly have done well in attempting to bring every kind 

 of disease into their system. But I find it extremely difficult 

 to do the same thing : and both from want of confidence in my 

 own knowledge, and from want of leisure, I have not attempted 

 to comprehend the whole of diseases, because I think it better 

 to leave the general plan imperfect than to introduce into it 

 any thing about which I am uncertain. While I only attempt 



