The most significant moment in Canto XV is the meeting between Dante and Ser Brunetto, Dante’s mentor and a source of encouragement. Dante was influenced by Ser Brunetto’s works, one of which he mentions—the Treasure.
This is one of the high points in the Inferno. Clearly, Dante felt that Ser Brunetto was an important man and cared for him deeply. When he addresses him (in the original Italian), for example, Dante uses the respectful form of “you,” something he does not do with the other shades. Brunetto Latini was one who understood Dante’s genius when others failed to do so. Now the poet still finds in his master the support and the encouragement that he needs to withstand the attacks that his fellow citizens are going to direct at him. In Brunetto Latini, Dante finds a sympathetic fellow artist, especially since he encourages Dante to follow his (Dante’s own) star to achieve the glorious fortune for which he is destined.
Dante consistently places men he respects in Hell, and he gives them the respect they are due in his meetings with them. However, respect and good deeds on Earth are not enough to survive damnation in Dante’s ideology.
At this point in his journey, Dante hears the third of three prophecies concerning his exile from Ser Brunetto. Brunetto prophesizes that Dante shall be hungered for on both sides, meaning that both political parties (the Guelphs and the Ghibellines) will hunger to destroy him. This is hardly a real prophecy, considering that the events Brunetto warns Dante about already came to pass well before Dante wrote Inferno.
The symbolism of the rain of fire and the scorching sand is that of sterility and unproductiveness: The rain should be life giving, the soil fertile. Instead, symbolically, the sex practices of the sodomite are not life giving.
