[IggleSniggle]

Holding long epic poems in your memory alone was once a celebrated skill.

[allturtles]

AFAIK the dominant theory is that they weren't memorized as a whole text, but composed on the fly with the help of a memorized set of stock formulas. [0]

[0]: https://poets.org/glossary/oral-formulaic-method

[AceyMan]

So, basically the ancient precursor to the skills of a good rapper.