Commentary Purg XXVI 137-138

Why does Dante now, in a canto composed of so much direct address, shift into indirect discourse?  Steiner (DDP Steiner.Purg.XXVI.137-138) was perhaps the first commentator to note that the style of the remark is 'elegant and studied in form,' as befits a discussion with Arnaut or any Provençal poet, all of whose verse is similarly ornate.  But Steiner does not remark upon the use of indirect discourse per se, nor does any other commentator.  In fact, Dante had already employed it in describing his oath to Guido ([Purg XXVI 104-105]).  A desire for stylistic variation may explain his choice, or there may be a more interesting reason that has escaped us.