Green is the colour of the Ovate, and under the sign of this colour are placed all the sciences of awen and reason and cogency, as distinct from what belongs to the principal sciences of Bardism, and all the improvement of sciences of whatever kind they may be, so that they are good. That is to say, they are assimilated to the green vegetation of the growth of earth, woods, and fields, which delights the heart and eye of those who behold them.
Barddas: The Triads of Privilege and Usage.
Iolo Morganwg was a stonemason. Most people who know anything about him could tell you that – but I suspect very few of them could tell you what it meant. Indeed, I suspect that, if pressed, people would guess it meant something like a bricklayer – a relatively unskilled manual job, of low social status.