The Barddas of Iolo Morganwg, Vol. I., ed. by J. Williams Ab Ithel, [1862], at sacred-texts.com
There are three primary elements, out of which proceed every other corporal substance, and living existence: the first is the calas, from which are all corporeity and hardness, that is to say, calas is the air, out of which, by compression, are derived every corporeity, colour, and form; the second is the fire, out of which proceed every motion and change; the third is the nwyvre, from which are God, and all life, understanding, and knowledge. Others say: Galas; uvel, and nwyvre, which is God. Others say: there are five special elements: earth, water, firmament, fire, and nwyvre. From the calas proceed every hardness, every corporeity, and every form and colour, and it is dark, whether it be liquefied or hard; from the uvel are fire, and all
heat and light, and all hue, and all motion and sensation; from the nwyvre are all life, and God, and soul, understanding, knowledge, and all affection and awen. And neither number, weight, or measure, can be applied to one or other of these three, where they are not mutually mixed together--nor knowledge, motion, hue, or form.
The Book of John Bradford.