Avenzoar, upon the whole, nearly agrees with Rhases, but expresses himself undecided with regard to the 20th and 21st days. His authority must also be allowed to be of great weight upon this subject, if we may believe Averrhoes, that he lived to the age of one hundred and thirty-five, and practised medicine from his fortieth year.
To the first class of critical days, according to Haly Abbas, belong the 7th and 14th; to the second, the 11th and 20th; to the third, the 4th, 17th, and 21st; and to the fourth, the 3d, 5th, 9th, and 18th.
Alsaharavius gives a similar list to Haly’s. He inclines rather to the 20th than the 21st day.
Galen, and most of the ancient authorities, believed that the critical days are influenced by the moon. Actuarius, in particular, attributes much to the influence of the sun and moon in influencing the course of fevers.
Prosper Alpinus gives a correct summary of the ancient doctrines respecting the critical days. (De præs. Vita et Morte ægrot. vi, 4.)
SECT. VIII.—THAT CRITICAL SYMPTOMS APPEARING IN THE COMMENCEMENT ARE UNFAVORABLE.
The signs of concoction are never unfavorable, for concoction always take place when nature prevails, and therefore the signs of it are always favorable. But the critical signs may sometimes appear unfavorably, owing to the crisis partaking of a double character (as was said with regard to the critical days), being sometimes favorable and sometimes unfavorable. They ought not therefore to appear at the commencement, nor during the increase of the disease, but after its acme, at which time nature is prevailing over the disease.
Commentary. The opinion here delivered is derived originally from Galen, but is maintained also by Oribasius, and the other authorities. It requires no comment.