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. SECT. IX.—HOW TO JUDGE BEFOREHAND OF A FUTURE CRISIS. If the paroxysms increase in violence, occur earlier, and become much stronger; if they invade on the third day; and if symptoms of concoction appear in the urine, alvine discharges, and sputa, the disease will certainly soon come to a crisis. If the attack is slow, and if the paroxysms occur at the same hour every day, you may expect that the crisis will not take place till after a longer time. And those fevers which make their attack with rigors cannot terminate until the rigor abate; for until that occur it is impossible for the disease to have attained its acme, and therefore much less is it reasonable to expect that it is upon the decline. * * * * * COMMENTARY. This Section is copied from Oribasius. (Synops. vi, 3.) The subject is fully treated of by Galen (de Crisibus.) Rhases describes very accurately the symptoms of an approaching crisis, such as, confusion of the understanding, vertigo, headach, inquietude, involuntary flow of tears, pain of the stomach, &c. He warns the inexperienced not to be alarmed at the violence of the precursory symptoms. (x, 26.) Avicenna, Averrhoes, Haly Abbas, and Alsaharavius, though they treat of the subject very fully, supply no original views. See an ample account of the ancient opinions in Prosper Alpinus. (De Præs. Vita et Morte ægrot. vi.) SECT. X.—HOW TO RECOGNIZE A PRESENT CRISIS.