Donkey milk knowledge archive · Historical source

Albertus Magnus, “De animalibus”: donkey milk is thin and low in cheese

Around 1260 Albertus Magnus explains in his book on animals that donkey milk is so thin that it contains little cheese and is therefore given to the wasting sick. Its whiteness, he says, is reputed to make the skin clean and bright – referring to Poppaea in Pliny.

Historical account: The information reproduced here reflects the knowledge of its time. It is not scientifically substantiated, is not a recommendation and cannot be applied to today. Donkey milk is a food, not a remedy.
c. 1260Cologne (Holy Roman Empire)Natural history textbook
Author
Albertus Magnus (c. 1200–1280), Dominican
Work
De animalibus libri XXVI, edition after the Cologne autograph by Hermann Stadler, 2 vols., Münster 1916–1920
Passage
Book XXII, tr. 2, c. 1, no. 7 “Asinus” (vol. 2, p. 1358); Book III, tr. 2, c. 9 (vol. 1, p. 351)
Time & place
c. 1256–1260 · Cologne (Holy Roman Empire)
Type of source
Natural history textbook

In the original words

What the original says

Ex siccitate etiam provenit quod lac feminae asinae adeo subtile est quod parum habet de caseo: et ideo datur [h]e[c]thicis. Albedo autem sua dicitur conferre ad munditiam et candorem cutis.

It also comes from [the animal’s] dryness that the milk of the she-ass is so thin that it contains little cheese; therefore it is given to those suffering from hectic fever [wasting]. Its whiteness is said to contribute to the cleanness and brightness of the skin.

LatinAlbertus Magnus, De animalibus XXII, tr. 2, c. 1, Nr. 7 (ed. Stadler, Bd. 2, S. 1358)

lac cameli est tenuissimum respectu lactis aliorum animalium, et in tenuitate proximum ipsi est lac equae et post illud lac asinae, et ideo consumptis datur ut humectet eos

Camel’s milk is the thinnest compared with the milk of other animals; closest to it in thinness is mare’s milk and after that the milk of the she-ass; and therefore it is given to the wasted to moisten them.

LatinAlbertus Magnus, De animalibus III, tr. 2, c. 9 (ed. Stadler, Bd. 1, S. 351)

English rendering: our own translation by the DON DONKEY’S editorial team, following the sense of the text.

Background

Who, when, what kind of text

Albertus Magnus was a Dominican, theologian and one of the most versatile natural philosophers of the Middle Ages; he taught in Paris and Cologne. His 26 books “De animalibus” were written around 1256–1260. The first 19 books comment on Aristotle’s zoological works in Latin translation; the remaining seven contain his own accounts, including an alphabetical list of animals with notes on keeping and uses.

The work survives in Albert’s own handwriting, now kept in Cologne. Hermann Stadler’s critical edition (Münster 1916–1920) is based on it. In the apparatus Stadler refers to Albert’s models, such as Pliny and Avicenna; in the text he marks the passages taken from Aristotle. The folio numbers of the manuscript are carried in the edition, so every passage can be traced back to the autograph.

Content

What the source reports about donkey milk

In the list of animals in Book XXII Albert describes the ass as a cold and dry animal. From this dryness he derives that donkey milk is so thin that it has little cheese; therefore it is given to patients with wasting fever. Its white colour “is said” to contribute to the cleanness and brightness of the skin, and he adds that according to Pliny, Poppaea bathed in warm donkey milk.

Already in Book III, in his treatment of Aristotle, Albert ranks the kinds of milk by thinness: camel’s milk thinnest, then mare’s, then donkey milk. It is given to the wasted to “moisten” them, because its small cheese content does no harm.

In the same section Albert reports how Tartars, Cumans and Ruthenians let mare’s milk ferment and drank it. This glance at the milk use of other peoples shows the author’s broad interest beyond medicine.

At a glance

Figures & facts from the source

26books make up “De animalibus”
p. 1358donkey milk in the entry “Asinus” (Book XXII)
p. 351kinds of milk ranked by thinness (Book III)
3kinds of milk in order: camel, mare, ass
1916–1920critical edition by Hermann Stadler

Critical assessment

How reliable is this source?

Source value

Albert’s own handwritten copy survives, and Stadler’s edition is based directly on it – a rare starting point for a 13th-century text. The passages are verifiable page by page. The square brackets in the quotation are the editor’s additions.

Own and borrowed material

Albert marks the skin-care statement with “dicitur” as tradition and bases it on Pliny. The explanation via the ass’s “dryness”, by contrast, is his own deduction within humoral theory.

Today’s assessment

That donkey milk is thin and low in casein is consistent with modern analyses. Giving it for wasting and the effect on the skin belong to the doctrine of their time and cannot be applied to today; donkey milk is a food.

Our assessment

Albertus Magnus combines the ancient tradition of Poppaea with a natural-philosophical explanation of his own. We particularly like the fact that his observation that donkey milk contains “little cheese” matches modern measurements of its low casein content.

Composition of donkey milk (review 2025)

References

Sources to check

More sources and studies in the research archive. Summarised by the DON DONKEY’S editorial team, as of November 2026.