FEVERS. 595 



and it is allowable to suppose that the like may happen with 

 respect to the exacerbations of continued fevers, so as thereby to 

 disturb the regular appearance of critical days. 



A particular instance of this occurs with respect to the sixth 

 day of fevers. In the writings of Hippocrates there are many 

 instances of terminations happening on the sixth day ; but it is 

 not therefore reckoned among the critical days ; for of the ter- 

 minations happening on that day, there is not one which proves 

 finally of a salutary kind the greater number are fatal, and 

 all the rest are imperfect, and followed by a relapse. All 

 this shews that some violent cause had, in these cases, pro- 

 duced a deviation from the ordinary course of nature ; that 

 the terminations on the sixth day are nothing more than anti- 

 cipations of the seventh, and therefore a proof of the power of 

 this last. 



CXVI. The doctrine of critical days has been much embar- 

 rassed by some dissonant accounts of it which appear in the 

 writings imputed to Hippocrates. But this may be justly ac- 

 counted for from these writings being truly the works of differ- 

 ent persons, and from the most genuine of them having suffered 

 many corruptions ; so that, in short, every thing which is incon- 

 sistent with the facts above laid down, may be ascribed to one or 

 other of these causes. 



CXVII. This, further, has especially disturbed the doctrine 

 of critical days, that Hippocrates himself attempted, perhaps too 

 hastily, to establish general rules, and to bring the doctrine to a 

 general theory, drawn from Pythagorean opinions concerning 

 the power of numbers. It is this which seems to have produced 

 the idea of odd days, and of a quaternary and septenary period ; 

 doctrines which appear so often in the writings of Hippocrates. 

 These, however, are inconsistent with the facts above laid down ; 

 and, indeed, as Asclepiades and Celsus have observed, are incon- 

 sistent with one another. 



CXVI II. Upon the whole, therefore, it is apprehended that 

 the critical days above assigned are truly the critical days of 

 Hippocrates, and may be consistently explained in the following 

 manner. 



CXIX. From the universality of tertian or quartan periods 

 in intermittent fevers, we cannot doubt of there being in the ani- 



