Substantial bodies of teaching were transmitted for generations before they were written down, and some remained oral long after writing was available. The accuracy came from method rather than from unusual memory.
Metre is a preservation device
Verse constrains what can be said. A line has a fixed number of syllables and a fixed pattern of stress, so a substituted word usually breaks the pattern audibly.
That constraint turns memorisation into a partly mechanical task. The reciter is not recalling free prose but filling a shape that rejects most errors.
Prose passages inside oral traditions tend to be shorter and more formulaic for the same reason, since they lack the metrical scaffolding that protects verse.
Redundancy lets errors be caught
Oral compositions repeat themselves deliberately. Epithets recur, phrases return in fixed slots, and whole passages appear more than once.
Modern readers sometimes treat this as padding. It functions instead as a checksum, because a repeated element that no longer matches its earlier appearance signals a fault.
Lists and genealogies work similarly. Their internal ordering is rigid enough that a missing item disturbs the sequence rather than passing unnoticed.
Transmission was collective, not individual
Recitation in most traditions happened in groups, with several people who knew the same material present at once.
A deviation is therefore audible to listeners who can correct it immediately. The unit of memory is the community rather than any single reciter.
Some traditions formalised this into examination, where a student recited before teachers who had themselves been examined, producing a chain of certified transmission.
Teaching methods were built around the text
Where accuracy mattered most, traditions developed drills that recombined a passage in fixed permutations rather than simply repeating it forwards.
Reciting in altered orders makes each word independently secured, so a memoriser cannot coast on the momentum of a familiar sequence.
Training began in childhood and continued for years, and the practice was usually inseparable from ritual duties that required the material to be produced on demand.
Writing changed the status of the spoken version
When texts were finally committed to script, the written copy did not always become the authority, and in some communities it was treated as distinctly secondary.
In several traditions the manuscript served only as an aid for a reciter who already knew the material by heart, and correct pronunciation, pacing and intonation remained things that only a living teacher could convey.
That relationship survives in liturgy today. A written text exists and is printed for everyone, yet the performance is still learned by ear from someone who learned it the same way, which keeps the oral chain intact alongside the book.