Commentary Purg XIV 55-57

This passage offers the occasion for a dispute among the commentators: does altri refer to Rinieri or to Dante?  (According to most early commentators, the former; to most later ones, the latter).  The major problem with the older hypothesis is that one has a hard time seeing what good it can do Rinieri to hear this news (and Guido's locution points to a potential benefit to his auditor), since he cannot intervene in worldly events, while Guido's unseen mortal interlocutor still has a life to live back on the earth -- indeed in Tuscany -- and may profit from this prophetic warning.

      Casini/Barbi (DDP Casini.Purg.XIV.57) seem to have been the first commentators to cite, for Dante's phrase vero spirto, John 16:13, 'Spiritus veritatis' (the Spirit of truth -- i.e., the prophetic capacity of the Holy Spirit); notice of this passage has become fairly commonplace, but represents a relatively recent discovery.  Guido openly calls upon the Paraclete, the Holy Spirit (John 16:7), as the guarantor of the truth in his words; Dante's own prophetic status in the poem is not put before us so straightforwardly, but is nonetheless perceptible.  See C.Purg.XXIV.52-54.