The Barddas of Iolo Morganwg, Vol. I., ed. by J. Williams Ab Ithel, [1862], at sacred-texts.com
. That is to say, they are called the three columns, and the three columns of truth, because there can be no knowledge of the truth, but from the light thrown upon it; and the three columns of sciences, because there can be no sciences, but from the light and truth.