In the mid-thirteenth century, a Dominican friar designed an experimental test of a common belief: that ostriches could safely consume iron. As he reports in De animalibus (‘On Animals’), the philosopher known to history as Albert the Great (c.1200–1280) offered several ostriches a choice between iron fragments, bones, and pebbles:

It is tempting to compare this passage to a modern single-variable experiment, with which it bears several similarities. Much like any scientist might today, Albert attempts to control for variables that are not the focus of his study: the bones are broken into small, edible pieces, presumably to match the sizes of other items, and multiple ostriches are recruited for a series of trials, minimizing the effects of outliers. Indeed, Albert's personal narratives have often fueled what Nigel Harris calls ‘extravagant claims … with regard to the modernity and originality’ of his methods; thus William Wallace describes Albert as ‘one of the outstanding forerunners of modern science’, aligning his emphasis on observation with empiricism.

Yet Albert's experiment is also rooted in methods typical of thirteenth-century philosophy and in long-standing ideas about the dietary habits of ostriches, which persisted for centuries after De animalibus; indeed, many early modern manuscripts depict ostriches with iron objects (figs 4.1, 4.2). The notion that these birds could digest iron dates at least to the ninth century, when a popular Arabic text on animals, Kitāb al-Ḥayawān by al-Jāḥiẓ (776–c.868), described an attempt to feed various items to an ostrich; this test subject willingly consumed metal, although it did not survive the experiment. Despite its divergent conclusions, Albert's experimental report is therefore itself an echo of this authoritative precedent. More broadly, Albert's observations throughout De animalibus are founded on the principles of Aristotelian science, with its emphasis on sense perception.