 Avicenna has a number of arguments attempting to show that an actual infinity in nature is impossible (for a presentation and assessment of some of these arguments see Zarepour 2020). These arguments can be divided into those that appeal to motion as part of the proof, and those that do not appeal to motion. Here I merely consider one of Avicenna’s non-motion proofs against an actual (spatial) infinity. The argument, which I present, is not the preferred proof in either The Cure or The Salvation, although he had toyed with it in The Cure (Avicenna, [Ph], 3.8 [5–7]). Still it is his preferred and indeed only argument against an actual infinity in his shorter and last philosophical encyclopedia, Pointers and Reminders (Avicenna, [PR], namaṭ 1, ch. 11, p.  183–90).[7]  Moreover, the proof is a uniquely Avicennan one. 