Isaac Israeli: donkey milk in the Liber dietarum universalium (1515 print)

Background

Who, when, what kind of text

Isaac Israeli was a Jewish physician and philosopher who worked for many years in Kairouan, among others in the service of the early Fatimids. His dates are uncertain; a very long life from the mid-ninth into the tenth century is usually assumed. His Arabic book on foods was translated into Latin by Constantine the African at Montecassino in the late eleventh century and, as the Liber dietarum universalium et particularium, became a core text of European dietetics.

The 1515 print gathers several works attributed to Isaac, together with other medical writings, under the title Omnia opera Ysaac. There the Liber dietarum universalium appears with the scholastic commentary of Petrus Hispanus, which divides the text into lectiones. The passage quoted here belongs to Isaac’s base text; the commentary begins at the foot of the same page. Abbreviations of the early print are expanded in the quotation.

Content

What the source reports about donkey milk

Isaac distinguishes milk by its thickness. He considers women’s milk the thinnest and places ass’s milk close to it in thinness. In a second group, “less thin”, ass’s and mare’s milk stand between camel’s and goat’s milk. Mare’s milk, he says, is warmer and closer to camel’s milk; ass’s milk is more balanced and closer to goat’s milk.

From this Isaac derives practical advice: drunk warm, ass’s milk curdles less in the stomach than goat’s milk, and with honey and a little salt not at all. It therefore loosens the bowels and softens hardened sinewy parts. In his account it also eases shortness of breath and cough and helps with injuries of the chest, kidneys and bladder.

This classification travelled on: in the thirteenth century Bartholomaeus Anglicus quotes Isaac at length in his chapter on milk. The statements reflect the humoral theory of the time and are not health claims valid today.