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Critical Days

Crises took place on what were called critical days. It is a commonplace that a disease tends to reach a crisis on a fixed day from the commencement, although the day is not absolutely fixed, nor is it the same for all diseases. The writer of Prognostic and Epidemics I. lays it down as a general law that acute diseases have crises on one or more fixed days in a series.

In Prognostic Chapter XX the series for fevers is given thus:--4th day, 7th, 11th, 14th, 17th, 20th, 34th, 40th, 60th.

In Epidemics I. XXVI. two series are given:--

a) diseases which have exacerbations on even days have crises on these even days: 4th, 6th, 8th, 10th, 14th, 20th, 24th, 30th, 40th, 60th, 80th, 120th.

b) diseases which have exacerbations on odd days have crises on these odd days: 3rd, 5th, 7th, 9th, 11th, 17th, 21st, 27th, 31st.

A crisis on any other than a normal day was supposed to indicate a probably fatal relapse.

Galen thought that Hippocrates was the first to discuss the critical days, and there is no evidence against this view, though it seems more likely that it gradually grew up in the Coan school.1

What was the origin of this doctrine? Possibly it may in part be a survival of Pythagorean magic, numbers being supposed to have mystical powers, which affected medicine through the Sicilian-Italian

[p. lv] school. But a man so free from superstition as the author of Epidemics I. was unlikely to be influenced by mysticism, particularly by a mysticism which left his contemporaries apparently untouched. More probably there is an effort to express a medical truth. In malarious countries, all diseases, and not malaria only, tend to grow more severe periodically ; latent malaria, in fact, colours all other complaints. May it not be that severe exacerbations and normal crises were sometimes confused by Hippocrates, or perhaps a series of malarial exacerbations attracted the crisis to one of the days composing it? The sentence in Epidemics I. XXVI. is very definitely to the effect that when exacerbations are on even days, crises are on even days ; when exacerbations are on odd days, crises are on odd days. Evidently the critical days are not entirely independent of the periodicity of malaria.

1 On the other hand, critical days are not discussed at all in Coan Prenotions, the supposed repository of pre-Hippocratic Coan medicine.

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