Donkey milk in history: Aristotle

Contents

1. The source in brief
2. The original text
3. Background
4. What the source reports
5. Numbers and facts
6. Critical assessment
7. Our assessment

In the 4th century BC, Aristotle ranked types of milk by their thickness: camel milk was the thinnest, followed by human and donkey milk, with cow milk being the thickest. Mare's and donkey milk were mixed into Phrygian cheese.

The source in brief

• Author: Aristotle
• Work: Historia animalium (Natural History)
• Passage: Book III, Ch. 20–21 (Bekker 521b–522a)
• Time and place: 4th century BC · Ancient Greece
• Type of source: Ancient natural history

The original text

Now the camel's milk is the thinnest, and that of the human species next after it, and that of the ass next again, but cow's milk is the thickest.

Camel milk is the thinnest, followed by human milk, then donkey milk; cow milk, however, is the thickest.

English, Hist. an. III 20, 521b (English translation by Thompson 1910)

Mare's milk, by the way, and milk of the she-ass are mixed in with Phrygian cheese.

Mare's milk and the milk of the she-ass are, by the way, mixed into Phrygian cheese.

English, Hist. an. III 21, 522a (English translation by Thompson 1910)

German translation: free, sense-for-sense translation by the DON DONKEY'S editorial team.

Background

Aristotle (384–322 BC) wrote the "Historia animalium", an extensive collection of observations on the anatomy, reproduction, and lifestyles of animals. The work was probably written in the 340s and 330s BC and draws on his own observations as well as reports from shepherds, fishermen, and hunters.

In the third book, Aristotle discusses the "like parts" of the body, including blood, fat, and milk. He describes milk as a mixture of a watery component (whey) and a solid component (curd); the thicker the milk, the more cheese could be obtained.

What the source reports

Aristotle establishes a ranking of types of milk by their thickness: camel milk is the thinnest, followed by human milk, then donkey milk; cow milk is the thickest. In doing so, he connects the observation that thin milk contains little curd.

In the continuation, he reports on cheese-making: mare's milk and donkey milk were mixed into Phrygian cheese. Donkey milk was therefore not only a subject of natural observation, but was also mentioned in Asia Minor as an ingredient in cheese preparation.

Aristotle does not mention medicinal uses of donkey milk in these passages. His statements are descriptive and comparative.

Numbers and facts

• 4 – Types of milk in the ranking by thickness
• 3rd – Place of donkey milk from thinnest to thickest
• Phrygia – Region whose cheese contained donkey and mare milk
• 521b–522a – Passage reference according to Bekker
• 1910 – Year of the cited English translation

Critical assessment

• Observation instead of recipe: The passage is one of the early natural history descriptions of donkey milk without medical intent. It classifies types of milk by visible properties.
• Contradiction in Pliny: Pliny the Elder adopts much from Aristotle, but in Naturalis historia 11,237 he calls donkey milk the thickest. The editor Mayhoff refers to Aristotle at this point; apparently Pliny altered or misunderstood his source.
• Comparison with modern analyses: Modern milk analyses (cf. archival studies 71 and 97) tend to support Aristotle's classification of "thin" milk rather than Pliny's statement.
• Limitations of the source: Aristotle's categories such as "thin" and "thick" are not measured values. The comparison with modern data is only a rough plausibility check.

Our assessment

We like the matter-of-factness of this passage: Aristotle compares without advertising. The note on Phrygian cheese also shows that donkey milk was already processed as a food in antiquity.

Reference: English translation by D’A. W. Thompson, 1910 (Elpenor), page with the milk ranking; Continuation: Milk and cheese, Phrygian cheese (Elpenor) · Summarized by the DON DONKEY'S editorial team, as of November 2026.

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End of the source summary. The source does not refer to DON DONKEY'S® or our products. Our donkey milk is a food.