In the sixth circle, Heretics, such as Epicureans (who say "the soul dies with the body") are trapped in flaming tombs. Dante holds discourse with a pair of Epicurian Florentines in one of the tombs: Farinata degli Uberti, a Ghibelline (posthumously condemned for heresy in 1283); and Cavalcante de' Cavalcanti, a Guelph, who was the father of Dante's friend and fellow poet Guido Cavalcanti. The political affiliation of these two men allows for a further discussion of Florentine politics (Canto X). Also seen here are Epicurus, Emperor Frederick II, and Pope Anastasius II.
      In response to a question from Dante about the "prophecy" he has received, Farinata explains that what the souls in Hell know of life on earth comes from seeing the future, not from any observation of the present. Consequently, when "the portal of the future has been shut," it will no longer be possible for them to know anything.
      Pausing for a moment before the steep descent to the foul-smelling seventh circle, Virgil explains the geography and rationale of Lower Hell, in which violent and malicious sins are punished. In this explanation, he refers to the Nicomachean Ethics and the Physics of Aristotle (Canto XI). In particular, he asserts that there are only two legitimate sources of wealth: natural resources ("nature") and human activity ("art"). Usury, to be punished in the next circle, is therefore an offence against both:
      From these two, art and nature, it is fitting,
      if you recall how Genesis begins,
      for men to make their way, to gain their living;
      and since the usurer prefers another
      pathway, he scorns both nature in herself
      and art her follower; his hope is elsewhere.

Taken from Dante's Inferno on Wikipedia