 According to Theophrastus (Metaph. 6a 19–22), Eurytus arranged pebbles in a certain way in order to show the number which defined things in the world, such as a man or a horse. Aristotle refers to the same practice (Metaph. 1092b8 ff.), and Alexander provides commentary on the Aristotelian passage (CAG I. 827.9). Aristotle introduces Eurytus as someone who regarded numbers as causes of substances by being the points that bound spatial magnitudes. He says that Eurytus made likenesses of the shapes of things in the natural world with pebbles and thus determined the number which belongs to each thing by the number of pebbles required. Scholars often treat Eurytus’ procedure as puerile and have sometimes not taken him seriously (Kahn 2001, 33), or suggested that Theophrastus is ironical in his presentation (e.g., Zhmud 2012, 410–411). There is, however, no obvious irony in Theophrastus’ remarks. He, in fact, presents Eurytus very positively as someone who showed in detail how specific parts of the cosmos arose out of basic principles, in contrast to other thinkers, who posit basic principles but do not go very far in explaining how the world arises from those principles. This positive presentation may reflect Theophrastus’ source, Archytas, who perhaps saw Eurytus as attempting to carry out Philolaus’ project of determining the numbers that give us knowledge of things in the world (Huffman 2005, 55; see also Netz 2014, 173–178).