Dante takes a step backward in his learning process in this canto. For the first time in Malebolge, Dante feels pity for the sinners in this circle, and Virgil chastises him for his behavior. Perhaps Dante wasn't ready to see the true nature of sin in those earlier cantos. Also possible is that Virgil is fallible and can also feel pity for some of the souls in Hell but not for those in the final circles.
In keeping with Dante's theme of Divine Retribution, the Fortune Tellers and Diviners have their heads on backwards and their eyes are full of tears. These are the souls who, on Earth, tried to see too far ahead of them, and thus will spend eternity forever looking behind with blurred vision. Following the teachings of the papacy, the theme of religion is broached, because the papacy did not approve of sorcery in any form.
For the first time, Dante violates his own concept of judging each spirit by the standards of the time in which he lived. Here he condemns the Greek prophets, who were held in high esteem in their own time. It is interesting that the Old Testament prophets are not here, and Dante offers no explanation for their absence.
