Look up at Cadair Idris from the Mawddach estuary and you can see why people named it a chair. The mountain curves round into a vast hollow, a cwm scooped out of the rock, with a dark lake — Llyn Cau — lying in its seat and the summit ridge rising behind like a high back. Cadair Idris: the Chair of Idris.
Who was Idris? The tradition is not sure, and that is part of the charm. Some say he was Idris Gawr, a giant who lived on the mountain and ruled the land around it. Some say he was a prince of Meirionnydd, a real warrior who fell in battle in the seventh century. The best-loved version makes him something rarer: a giant who was also a poet, a philosopher and an astronomer, who would sit in his great stone chair night after night and study the stars.
It is not hard to believe. On a clear night on Cadair Idris, away from any town, the sky is absurd with stars — the Milky Way arching overhead, the constellations crowding so thickly you lose the familiar shapes. A giant with time on his hands and a whole mountain for a seat could learn a great deal up there.
And that is where the warning comes from. Welsh tradition says that anyone who spends a night alone on Cadair Idris will come down in the morning in one of three states: a poet, a madman, or dead. Some tellings add that the mountain is a place where the Cŵn Annwn, the hounds of the otherworld, run on stormy nights. Others say the lake in the chair is bottomless, and no bird will fly across it.
The three outcomes are the heart of it. Poetry, madness and death are all things that come from staying too long near something bigger than yourself — the stars, the night, the old powers in the rock. Some people come back with words they did not have before. Some come back unable to find their words at all. Some do not come back. In the Welsh imagination, inspiration was never safe. Taliesin got his genius from three scalding drops of a witch's brew; a night in Idris's chair was the mountain's version of the same deal.
Walkers still climb the Minffordd path past Llyn Cau, or the Pony Path up from Tŷ Nant, and plenty of them — less wisely — camp near the summit shelter to watch the sunrise. So far, most seem to come down as themselves. Though if you ask around Dolgellau, someone will always know someone who came down a little bit odd, and started writing poetry.
Wear Cadair Idris and you wear that old Welsh bargain: sit with the stars long enough, and you may come back wiser — or wilder — than you went up.