Commentary Par XXXIII 145

While the fact that the word stelle is the last word of each canticle would seem to have been an early and lasting perception, John of Serravalle (DDP Serravalle.Par.XXXIII.133-145) appears to have been the first ever to have it.

For the possibility that Dante's stella reflects Ovid's astra (Metam. XV.876) and his starry vision of his own personal immortality that concludes his great poem (Metam. XV.871-879), reformulated by Dante to accord with quite a different (and less self-absorbed) view, see Levenstein (Leve.2003.1), p. 418.

For an essay on this 'last word,' see Ahern (Aher.1984.1), who, while not referring to Ovid, argues that this canto couches its central concerns, conflating two metaphors, in the images of the heavens as book and of the stars as alphabet.

Scartazzini (DDP Scartazzini.Par.XXXIII.145) points out that the presence of the same form of the verb muovere in the first and last lines of the cantica creates a sort of ring composition.  He also points out that Dante's practice in this regard resembles that found in canzoni of other poets in his time; he also suggests the pertinence of the ending (which happens to constitute its thirty-third paragraph) of the Epistle to Cangrande (Epist.XIII.90): 'And since, when the Beginning or First, which is God, has been reached, there is nought to be sought for beyond, inasmuch as He is Alpha and Omega, that is, the Beginning and the End, as the Vision of John tells us, the work ends in God Himself, who is blessed for evermore, world without end' (tr. P. Toynbee).