De Secretis Mulierum et Virtutibus Herbarum, Lapidum et Animalium

Albertus Magnus's Little Book,

...and as frequently happens in the fourteenth year fourteen was considered the standard age for the onset of puberty in medieval medical texts. And the menstrual flow begins to occur in every month for the purpose of nature's cleansing. For some, this flow occurs during the new moon, and for others later; thus, not all women suffer this affliction original: "dolorem"; literally "pain" or "suffering," referring to the monthly period at the same time, because in that flow everyone experiences it differently—some more, some less—and for some it lasts longer. This depends on the specific needs and the bodily temperament complexionem: the unique balance of the four humors—blood, phlegm, yellow bile, and black bile—within an individual of the women.

Here the author presents a noteworthy point, as is evident in the text. It may be questioned why the flow of sperm is not monthly, like the menses? It is answered that sperm, or the seed of the man, is more highly "cooked" original: "decoctum"; medieval biology held that semen was a highly refined or "concocted" form of blood, processed by the body's heat and subtle; therefore, nature does not willingly discard it, but rather preserves it for generation, or for nourishment should a fetus original: "fœtus" require it. It is questioned why urine, defecation original: "stercorizatio", and sweat do not follow the movement of the moon like the menses? It is answered that urine and impurities are produced every day from the excess of food, according to their great heaviness and larger quantity; therefore, it is necessary that they be expelled daily. Note that young women are very moist; therefore, they naturally menstruate at the beginning of the month, while older women do so at the end because they are less moist. Note that dark-skinned women have less menstrual flow than fair-skinned women, because although all women are of a phlegmatic temperament phlegmaticæ complexionis: a constitution dominated by the "cold and moist" humor, phlegm, which was thought to be the primary humor of women, some are more so than others. And the more women consume delicate and well-peppered foods, the more refined a menstrual flow they emit. And the opposite—