CERBERUS IN ROMAN AND MODERN LITERATURE.
Neither Greek literature, nor Greek art, however, really seems to fix either the shape or nature of Kerberos; it was left to the Roman poets to say the last word about him. They finally settle the number of his heads, or the number of his bodies fused in one. He is triceps "three-headed," triplex or tergeminus "threefold," triformis "of three bodies," or simply Tricerberus. Tibullus says explicitly that he has both three heads and three tongues: cui tres sint linguæ tergeminumque caput. Virgil, in the Æneid, vi. 417, has huge Cerberus barking with triple jaws; his neck bristles with serpents. Ovid in his Metamorphoses, x. 21, makes Orpheus, looking for dear Eurydice in Tartarus, declare that he did not go down in order that he might chain the three necks, shaggy with serpents, of the monster begotten of Medusa. His business also is settled for all time; he is the terrible, fearless, and watchful janitor, or guardian (janitor or custos) of Orcus, the Styx, Lethe, or the black Kingdom.[9] And so he remains for modern poets, as when Dante, reproducing Virgil, describes him:[10]
"When Cerberus, that great worm, had seen us
His mouth he opened and his fangs were shown,
And then my leader with his folded palms
Took of the earth, and filling full his hand,
Into those hungry gullets flung it down."
Or Shakespeare, Love's Labor Lost, v. ii: "Great Hercules is presented by this imp whose club killed Cerberus, the three-headed canis."