In Dante Alighieri's The Divine Comedy Vol. I: Inferno, as readers follow the pilgrim's descent through the many circles of hell hell, monsters from classical mythology. Cerberus is one such monster that the pilgrim encounters on his voyage through hell. Cerberus's role in classical mythology transitions well into his new role in the Inferno, also Cerberus has many similarities with both the devil and the she-wolf, and Cerberus is the best match for his role as guard and punisher in the third circle of Hell.
During the Hellenistic era, or the time when Greek culture and ideas were in a golden age, mythology blossomed. Out of this mythology sprang new monsters with frightening looks and attitudes. Among them, was the three headed dog Cerberus. According to myth Cerberus was the off spring between the monsters Typhon and Echidna he was also brother to the Hydra and the Chimaera. His role, Grant and Hazel maintain, was "To 'devour' any of the inmates of the realm of Hades who tried to escape". This transitions perfectly for his role in the Inferno which is to be the guard of the gluttons, because in classic myth he greedily devours escaping shades, thereby being a glutton himself.
In classical mythology as in the Inferno, Cerberus did not welcome the living into the underworld, or in Dante's case the third circle of hell. There were several instances however in mythology when
Cerberus allowed mortals to pass. In one such instance the great minstrel Orpheus charmed him with his music so he could go onto Hades to recover the shade of his wife. In another instance, when Aeneas descends to the underworld accompanied by Sibyl of Cumae, when they reached Cerberus she "threw him a sop (cake soaked in drugged wine) to get past him" says Grant and Hazel. This marks a striking resemblance to how the pilgrim got past Cerberus "My master stopped and, spreading wide his finger...