The Barddas of Iolo Morganwg, Vol. I., ed. by J. Williams Ab Ithel, , at sacred-texts.com
Before the time of Belief and Baptism a letter was called gogyrven (from corf 2); and its right name is still gogyrven on the Coelbren--others call it cyrven. The old men--the primitive teachers--inserted in vocal song the number of the rays of every cyrven, and thus kept the memory and knowledge of them.
After plagawd had been obtained, that is, the dressed skins of animals, writing with black, or ink, came into use; and thence was introduced the practice of writing with ink on the Coelbren and its staves, instead of cutting cyrvens, which is still seen in places that are not visited, and are not much known. And thus were memorials and computation kept on wood and boards, and on stones, where it was possible to get them.
The three primary gogyrvens are .
There were sixteen gogyrvens before the faith in Christ; after that eighteen, then twenty.
Talhaiarn appointed twenty gogyrvens.
69:2 A body.