Commentary Par VII 13-15

In an exerted tercet, the poet says that he bowed his head, under the sway of his devotion to Beatrice, just as does a man who nods off to sleep.  For the same phrase, 't'assonna,' see [Par XXXII 139].  There it precedes the vision of the Godhead, featuring the miracle of the Incarnation.  It is perhaps not accidental that this is a central subject in Beatrice's long disquisition that begins at verse 19 and runs the rest of the canto.