In the introduction - beside a passage of the Aeneid - is discussed at lengh the Gospel about the Probatica pool in Jerusalem, insisting on the symbolism of water.  In the main body, part of the discussion is about vices, but then the sermon focuses on contrition, with references also to the importance of tears (link with the water in the Gospel of the day). The sermon ends with 's quotation from Purgatorio 9, which serves to introduce the divition of penance in contrition, confession, satisfection (topos), hence linking the sermon with those of the following days