 Cook Wilson is mainly remembered today for two contributions to Plato studies, foremost for his paper ‘On the Platonist Doctrine of the ἀσύμβλητοι ἀριθμοί’ (OPD), which bears on the debate on ‘intermediates’ in Plato. This issue originates in Aristotle’s claim in Met. A 6 987b14–17 that Plato believed that the objects of mathematics occupy an “intermediate position” between sensible things and Ideas/Forms. Since there is no explicit commitment to this claim in Plato, scholars either rejected Aristotle’s testimony or looked for passages where Plato might be said to have implicitly endorsed it, such as the Line at the end of Book VI of the Republic. Cook Wilson argued against reading this passage as implicitly endorsing ‘intermediates’, claiming that objects of thought (διάνοια) are Ideas, because Plato stated in Rep. 511d2–3 that they are “intelligible given a principle” (καίτοι νοητῶν ὂντων μετ’ ἀρκῆς), and, as Cook Wilson saw the matter: “nothing but an ιδέα can be an object of νοῦς” (OPD, 259).