The Barddas of Iolo Morganwg, Vol. I., ed. by J. Williams Ab Ithel, , at sacred-texts.com
p. 114 p. 115
There are three kinds of symbol: the symbol of letter, which the ancient authors called the symbol of cyrven; the symbol of number; and the symbol of blazonry, as a coat of arms, which belongs to the art of a herald-bard.