Earlier allusions to the myth possibly occur in the works of the poet Pindar, Plato, and Plato's student Xenocrates. A fragment from a poem, presumed to be by Pindar, mentions Persephone accepting "requital for ancient wrong", from the dead, which might be a reference to humans' inherited responsibility for the Titan's killing of Dionysus. Plato, in presenting a succession of stages whereby, because of excessive liberty, men degenerate from reverence for the law, to lawlessness, describes the last stage where "men display and reproduce the character of the Titans of story". This Platonic passage is often taken as referring to the anthropogony, however, whether men are supposed by Plato to "display and reproduce" this lawless character because of their Titanic heritage, or by simple imitation, is unclear. Xenocrates' reference to the Titans (and perhaps Dionysus) to explain Plato's use of the word "custody" ("φρούρα"), has also been seen as possible evidence of a pre-Hellenistic date for the myth.