Commentary Par XIII 16-18

Still another troubled tercet.  The first difficulty that it presents is fairly easy to resolve: Does the second circle extend beyond the first or does it stand within it?  Most commentators sensibly take the first view, since the third circle clearly is wider than the second ([Par XIV 74-75]), which at least implies that the second is wider than the first and, indeed, contains it.  The really obdurate problem, on the other hand, is how to construe verse 18.  If one says 'one went first and then the other followed' (as we translate the line), the meaning is that one of the circles only begins to move after the other does (and probably the first is followed by the second).  This hypothesis is seconded by the rhyme position of the word poi, used for the only time in the poem as a substantive, a usage that pretty clearly is forced by rhyme.  What would Dante have said had he been writing parole sciolte (words not bound by meter -- see [Inf XXVIII 1]), and not been constrained by the need to rhyme?  A good case can be made for 'secondo' (i.e., next).  And for this reason, we have translated the line as we have.  See also Fasani (Fasa.2002.1), p. 194, buttressing this position with the early gloss of Francesco da Buti (DDP Buti.Par.XIII.1-21).  Nevertheless, a strong and continuing tradition (including such worthies as Cristoforo Landino [DDP Landino.Par.XIII.18] and Alessandro Vellutello [DDP Vellutello.Par.XIII.16-21]) sees the verse as meaning that the circles move in opposite directions.  Countering this view, Trifon Gabriele (DDP Gabriele.Par.XIII.18), maintains that the line refers to the sequence of movements, as does Tommaseo (DDP Tommaseo.Par.XIII.16-18), who refers to the similar locution found at Conv.IV.ii.6: 'Lo tempo… è "numero di movimento secondo prima e poi"' (Time… is 'number and motion with respect to before and after' [Dante is citing Aristotle, Physics IV], tr. R. Lansing).  Scartazzini (DDP Scartazzini.Par.XIII.18) reviews the various shadings of the two major construings and throws up his hands, leaving the matter unresolved and passing on to other things.  In the next thirty-five years most who dealt with the problem followed Landino's solution.  Then, after centuries of inconclusive debate, refusing to choose between the two established and conflicting views, Trucchi (DDP Trucchi.Par.XIII.16-18) came up with a new hypothesis: Since the two concentric circles move so that the rays sent out by each reflect one another perfectly (he was thinking of facing pairs, Thomas and Bonaventure, Siger and Joachim, etc.), the circles, since they are of different extent, to maintain this unwavering relationship between themselves, must move at different speeds.  Giacalone (DDP Giacalone.Par.XIII.16-18) shares Trucchi's view, but credits Buti's less clear statement with having prepared the way.