It is most probable that this idea of planetary regency, however it might have arisen, or to whatever extent it may have been credited, received in the Arabian school, the stamp by which its currency has been subsequently maintained. For the revival and dispersion of ancient medical knowledge, we are confessedly under considerable obligations to the Arabians;[16] and more especially for the incorporation of astrology, magic and alchymy, with medicine.
Popular superstitions and national proverbs, are seldom without some foundation; and with respect to the present, it may be observed, that if it were not in some degree rooted in fact, and trained up by observation, it would become difficult to ascertain how such an opinion came to be adopted; and this investigation is rendered still more important from the consideration, that the existing law in this country, respecting insane persons, has been established on the supposed prevalence of this lunar regulation. A commission is issued, de _lunatico_ inquirendo, and the commissioners sitting for that purpose, are particular in their enquiries, whether the patient enjoys lucid intervals. The term _lucid interval_ has been properly connected with the word _lunacy_; for, if the patient, as they supposed, became insane at particular changes of the moon, the inference was natural, that in the intervening spaces of time he would become rational.
It is more than probable, that the origin of this supposition of the lunar influence may be traced to the following circumstances. The period of the return of the moon, and of regular menstruation in women, is four weeks; and the terms which designate them, have been imposed from the period of time in which both are compleated. Insanity and epilepsy are often connected with menstruation, and suffer an exacerbation of their paroxysms at the period when this discharge happens, or ought to take place. If, therefore, the period of menstruation in an insane woman should occur at the full of the moon, and her mind should then be more violently disturbed, the recurrence of the same state may be naturally expected at the next full moon. This is a necessary coincidence, and should be discriminated from effect. But such has been the prevalence of this opinion, that when patients have been brought to Bethlem hospital, especially those from the country, their friends have generally stated them to be worse at some particular change of the moon, and of the necessity they were under, at those times, to have recourse to a severer coercion. Indeed, I have understood from some of these _lunatics_, who have recovered, that the overseer or master of the work-house himself has frequently been so much under the dominion of this planet, and keeping steadily in mind the old maxim, _venienti occurrite morbo_, that, without waiting for any display of increased turbulence on the part of the patient, he has bound, chained, flogged, and deprived these miserable people of food, according as he discovered the moon's age by the almanack.