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The Astrological Physician

Lunar Cycles and the Judgment of Critical Days in Early Modern Medicine

A historical exposition of how physicians once determined the turning points of a disease by observing the Moon's position and aspects relative to its place at the onset of illness, including rules for identifying critical and judicial days and the astrological conditions that were thought to signal danger or recovery.

By Sage Davis3 min read

The true crisis of an illness was determined by the Moon's motion—specifically, by her square and opposition to the sign, degree, and minute she occupied when the patient first fell ill. To identify the exact crisis or critical days, the following rules were observed:

  1. At the moment the patient first fell sick, the Moon's place was to be precisely rectified: note the sign, degree, and minute of the Zodiac in which she was then placed.
  2. Observe when she reaches the square of that place, for that is the first crisis.
  3. When the Moon arrives at her true opposition—that is, the point opposite to where she was at the onset of illness—that is the second crisis.
  4. When she comes to the next square, it is the third crisis.
  5. When the Moon has completed her circuit of the heavens and returns to the very same sign, degree, and minute she held at the time the patient first fell sick, that is the fourth crisis.

The judicial days are the midpoints between two crises. An alteration or sudden change in the disease may also be discerned when the Moon is 45 degrees distant from her true place at the onset of illness, likewise at 90 degrees, and again at 135 degrees. Just as the crisis is the sudden change of the disease—an alteration for better or worse, tending either toward health or toward further sickness—so the critical and decretory days offer a more certain and sure judgment, whereby the physician may fully discern which way the disease will tend, or whereby the crisis may be exactly judged. For the decretory or critical days declare a surer judgment of the infirmity afflicting—whether it will be more powerful or in lesser measure at those times when the exact crisis occurs. When the crisis comes, there is a sharp contention between nature and the disease; if at that time nature is more prevalent than the disease, it is a good sign, but on the contrary, if the sickness prevails, then the crisis is dangerous. The fuller treatment of these matters is left for another occasion; meanwhile, observe these aphorisms by the way.

  1. Since it is most certain that the Moon by her motion shows the true crisis, and that the judicial or critical days are also found by her motion in the Zodiac, we must take care to consider how she is disposed—whether fortunate or unfortunate—and how she is aspected by the benevolent planets or by the malevolent and malignant planets. Further observe, at the time of the true crisis, whether she is in configuration with the lord of the sixth house or the lord of the eighth; for if at the crisis she is in any malevolent aspect of the lord of the sixth, it is an ill sign, and likewise if she is afflicted by the lord of the eighth, it gives great cause to judge the death of the sick party at that crisis.
  2. If she is then going to the square or opposition of the lord of the sixth, the disease and sickness increase; if she is fortunately aspected at the time of the crisis by Jupiter or Venus, and they are not lords of the sixth, eighth, or twelfth houses, it is a good crisis.
  3. The Moon transiting the cusps of the twelfth, eighth, or sixth houses at the time of the crisis gives cause to fear death or prolongation of the disease.
  4. On judicial days, the Moon fortunate and well aspected declares that a good crisis is to be expected; but if she is unfortunate, she declares the contrary.

Some hold that the seventh and fourteenth days are critical, and that these days after the patient first falls sick are the first and second crises—an opinion considered quite absurd, since the critical and decretory days do not proceed from inferior causes as some men think. The learned observe that the Moon has great influence and dominion over our inferior bodies, whereby the humors are stirred by her motion, and thereby the true crisis of the disease is declared. Because the Moon sometimes moves very swiftly and at other times very slowly, being often inconstant in her motion, she makes the true crisis not every seventh day, as many conceive. But these matters will be spoken of more copiously in another treatise hereafter; for the present, let the former rules suffice.

FINIS.

  1. The original book, as published in 1656, used the spelling “Physitian.” Here, the word has been changed to the modern spelling “Physician.”

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