The Barddas of Iolo Morganwg, Vol. I., ed. by J. Williams Ab Ithel, [1862], at sacred-texts.com
There have been three symbols of sciences in use by the nation of the Cymry from the beginning.
The symbol of word and speech, that is to say, a letter, ten fold, sixteen fold, twenty fold, and twenty-four fold.
The first of the three, in respect of privilege and origin, is the symbol of word and speech, that is to say, a letter.
The second, the symbol of harmony, that is to say, tone and music.
The third, the symbol of number, which is thus,--
That is to say, one, two, three, four, five, six, seven, eight, nine, ten, one-ten and one, one-ten and two, one-ten and three, one-ten and four, one-ten and five, one-ten and six, one-ten and seven, one-ten and eight, one-ten and nine, two-tens; and as before to three-tens, four-tens, five-tens, six-tens, seven-tens, eight-tens, nine-tens, a hundred; and to a thousand; and from thence to ceugant. It is a secret kept from the beginning by the voice of the Gorsedd of the Bards of the Isle of Britain; and it was first appointed as a special art in the sciences of wisdom by Tydain, father of Awen, who also arranged the symbols of the art of musical
harmony, in respect of voice, string, and bellows, as is exhibited in the memorials of the Bards of the Isle of Britain. (From the Second Book of the Secret of the Bards of the Isle of Britain, and from the Yniales. 1)
Let the following be added to the above system of symbols; , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , , or ; but some put for a hundred, and for a thousand.
99:1 p. 98 "The Yniales. That book, the work of Hopkin ap Thomas of Glyn Tawy, contained various matters, memorials, and sciences appertaining to things advantageous to be known. He lived in Ynys Tawy, and made the Gwernllwyn Chwith. Llywelyn the Red, son of Meurig the Aged, sang his praise."--MS.
In a poem addressed to Hopkin ap Thomas by Davydd y Coed, who flourished 1300--1350, mention is made of the Yniales as being in the former's possession.
"------ There are in his court,
The golden oak, Elucidarius,
And the Great and Yniales."--Myv. Arch. vol. i. p. 494.