There is something symptomatic in the fact that integrity control for stories “of feats” appeared in skaldic poetry in the VIII–IX centuries, and for monetary operations — in the XIV century, in the form of the famous double-entry bookkeeping.

Moreover, the skalds had three methods of “protection” at once, which reinforce each other:

• Dróttkvætt — the “courtly” meter of the skalds.

• 8 lines in a stanza.

• In each line ~6 syllables and 3 accents.

• Internal rhymes in a line: in odd lines — partial, in even lines — full.

• Alliteration connects lines in pairs (the odd line sets the sound, the even line picks it up). Why this is needed: if you mess up syllables/accents/rhymes, the form “breaks”, and the error is immediately audible.

• Alliteration — repetition of the initial sound in stressed words.

• Connects words and lines, sets the “skeleton” of memory.

• Example (in Russian, imitation): Veter vvys’ vzvyl; volny vo t’me. Why this is needed: if one “supporting” sound falls out, the ear catches the falsity.

• Kennings — stable poetic paraphrases (metaphorical formulas).

• “sea” = “whale-road”, “sword” = “blood-snake”, “poet” = “bee of the honey of poetry”.

• Use well-known schemes “main word + determiner”. Why this is needed: mix up a link — you break the sense/rhythm; the listener will notice.