Of the critical days, some terminate the disease frequently, faithfully, well, completely, clearly, decidedly; and others contrariwise to these. But the 13th has been shown to possess an intermediate character. Some of these are such as to prove critical if they experience even the most moderate impetus of nature, such as the 7th and 14th; whilst most of them prove critical in violent commotions of the system, but not otherwise. Neither are the favorable all equally favorable, nor the unfavorable all equally unfavorable; nor is their favorableness and unfavorableness according to any order. Those in the first rank of favorable days may be arranged thus: the best of all are the 7th and 14th, next to them the 9th, and 11th, and 20th; and near to them the 17th and 5th, after these the 4th, after it the 3d and 18th. Opposed to them, of the second rank, are these: the worst, which proves obscurely critical with danger, and is, as it were, diametrically opposed to the 7th, is the 6th: near to it are the 8th and 10th, after these the 12th, 16th, and 19th. Intermediate between these is the 13th, being neither so objectionable as those of the second rank, nor so powerful in freeing from diseases as those of the first. The critical days then are thus arranged according to their degree by Galen. Numerically thus: the favorable are the 3d, 4th, 5th, 7th, 9th, 11th, 14th, 17th, 18th, 20th; the unfavorable, the 6th, 8th, 10th, 12th, 16th, 19th; the intermediate, the 13th. Some of the critical days give information concerning the others, and are hence called indicatory by Hippocrates, because they indicate the crisis that is to happen on another critical day. Thus the 4th indicates a crisis on the 7th, by inducing sweats, perspirations, or some such particular evacuation, or by displaying certain signs which had not formerly taken place, or some symptoms of concoction. Galen says that the 4th is indicatory of the 6th, although it be unfavorable, as the 11th is of the 14th, and the 17th of the 20th. Until the 14th day the crises are the most decided, next to these until the 20th; from the 20th to the 40th they gradually lose their decided character. Of these, the first in degree are the 27th, 34th, and 40th, after which are the 24th and 32d. The other numbers intermediate between the 20th and 40th are indeterminate, and those after the 40th are not properly critical, as they terminate diseases by concoctions and abscesses rather than by crises. Hippocrates seems entirely to disregard all those after the 40th day, yet he enumerates the 60th, 80th, and 100th. After these, he says that some diseases prove critical in seven months, some in seven years, and others, as it would appear, in twice or thrice seven years.
Commentary. The Father of Medicine who was profoundly skilled in Semeiology, appears to have attached great importance to the observance of the critical days. At first, as Galen remarks, he seems to have been undecided respecting certain days, and, accordingly, he gives a somewhat different list of them in his ‘Prognostics’ and ‘Aphorisms,’ from what he has given in his ‘Epidemics.’ His latter list of critical days differs little or nothing from that of Galen.
Galen reposes such confidence in the doctrine of critical days, that he affirms that, by a proper observance of them, the physician may be able to prognosticate the very hour when a fever will terminate. The following is his list: The 7th is particularly favorable; next, the 14th; next to these, the 9th, 11th, and 20th; then the 17th and 5th; afterwards the 4th, 3d, and 18th. The 6th is very doubtful and unfavorable; the 8th and 10th, like the 6th; the 12th, 16th, and 19th, like the 8th and 10th. Intermediate between these two lists of favorable and unfavorable days is the 13th. He informs us that Diocles and Archigenes held the 21st to be particularly favorable, but he agrees with Hippocrates in rejecting it and adopting the 20th.
Celsus follows the system of Archigenes. He says, “κρίσιμοι dies erant, dies tertius, quintus, septimus, nonus, undecimus, quartus-decimus, unus et vicesimus; ita ut summa potentia septimo, deinde quarto-decimo, deinde uni et vicesimo daretur.” But he does not hesitate, afterwards, to express his distrust in the whole system; for, he adds, “verum in his quidem antiquos tunc celebres Pythagorici numeri fefellerunt; cum hic quoque medicus non numerare dies debeat, sed ipsas accessiones intueri.”
The Greek writers subsequent to Galen adopt his system, with little or no alteration. Aëtius arranges the critical days thus: First in order, the 7th and 14th; then the 9th and 11th; next to them the 17th and 5th; then, the 4th; and afterwards the 3d and 20th. The 6th is usually bad.
The last of the ancient authorities, Actuarius, is very full and confident in laying down the received doctrines, with regard to the critical days. He follows Galen.
The Arabians, with scarce one exception, adopt the Galenic system. Avicenna, who treats of the critical days very fully, mentions the list of them given by Hippocrates and Galen, and also that by Archigenes, but decides in favour of the former.
Rhases mentions the critical days in the following terms: The 3d is critical in very acute fevers; the 4th is indicative of the 7th and 6th; the 5th is favorable; the 6th generally unfavorable; the 7th is a particularly favorable or unfavorable crisis; the 8th rarely critical, but if it be, unfavorable; the 11th critical and indicative of the 14th; the 12th rarely critical, and like the 8th; the 13th rarely critical; the 14th, critical and favorable; the 15th like the 13th; the 16th like the 12th; the 17th like the 9th, and indicative of the 20th; the 18th rarely critical, or unfavorable; the 19th rarely critical, or, if so, not bad; the 20th next to the 14th, and favorable; the 21st sometimes critical, but less frequently so than the 20th; the 24th resembling the 20th; after these the 27th, 31st, 37th, and 40th are critical. Averrhoes remarks, that great deference is due to Rhases’ opinion upon this subject, since it was confirmed by experience, in more than ten thousand cases, in an infirmary (in infirmaria Relenson). His list is very little different from that of Galen. In his ‘Continens,’ he gives an account of the system of Archigenes, but prefers that of Hippocrates. (xxxii.)
Averrhoes states that the medical world was divided between the systems of Archigenes and Galen, but he inclines to the side of the latter in this case, although on most occasions given to dispute his authority.