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.
Chapter XX the series for fevers is
given thus:--4th day, 7th, 11th, 14th, 17th, 20th,
34th, 40th, 60th.
I. XXVI. two series are given:--
) diseases which have exacerbations on even
days have crises on these even days: 4th, 6th, 8th,
10th, 14th, 20th, 24th, 30th, 40th, 60th, 80th,
) 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
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.