At the centre of all the worlds — further down than the roots of the mountains, further in than the middle of the sea — there grows a tree. It is an ash tree, the greatest thing that has ever lived, and its name is Yggdrasil. Its branches hold up the sky, and birds you and I will never see nest in the light of its highest leaves. Its roots go down into three lands, and under one of those roots, in the blue-grey country of the giants, there is a well.
It is not a wishing well. It is older and stranger than that. Its water is dark and very still, and in the stillness there is everything: everything that has happened, everything that is happening, and the long quiet shape of everything to come. Whoever drinks from that well understands the world — not the way you understand a sum, but the way you understand a song. And beside the well, in all weathers, sits its keeper: an old, deep-voiced being named Mimir, who drinks a little of the water every morning, and says very little, and knows very nearly everything.
Now Odin, the highest of the gods, had a hall with a silver roof and a throne from which he could see the whole world at once. He had two ravens who flew out every morning and whispered the day's news in his ears. He had an army of the bravest souls, and a spear that never missed, and the love and fear of every living thing. And none of it was enough — because Odin could see that a hard day was coming, far off, the way you can smell rain before it falls, and seeing is not the same as understanding. So one grey morning he wrapped himself in a traveller's cloak, and pulled a wide hat down over his brow, and walked down the long root of the world-tree to the well, and asked the keeper for a drink.
Mimir looked at the king of the gods for a long, quiet time. Wells like this one do not give their water away, and Mimir did not make exceptions, not even for family, not even for kings. 'One drink,' said Mimir at last, 'costs one eye. Your own. Left in the water, forever.' He did not say it to be cruel. It is simply the oldest rule there is: the things that matter most are the things that cost us something, and wisdom — real wisdom — costs the most of all.
And here is the part of the story that people have wondered at around fires for a thousand years and more. Odin did not argue. He did not offer gold instead, though he had rooms of it, or his spear, or his throne, or a hundred years of service. He understood — perhaps he was already a little wise, to understand it — that the well was not bargaining. The price was the price. And he decided that half of everything he could see was a fair trade for the whole of everything there was to understand. So the Allfather paid.
We will let the quiet of the well cover the moment itself. Say only this: when it was done, Odin knelt and drank, and the water was cold and tasted of the beginning of the world, and understanding came into him like light coming into a room — slowly, and then all at once. He saw how all the stories fit together, the sad ones and the bright ones. He saw what the price of things was, and why it must be paid gladly or not at all. And they say he stood at the well a long while, watching, and then laughed softly, once, and went back up the long root to the morning, one eye the poorer and a whole world the wiser.
His eye stayed in the well. It is there still, they say, resting in the dark water like the moon resting in a midnight lake, seeing everything from below while Odin sees everything from above. And that is why, in all the old carvings and all the old tales, the wisest of the gods has one eye and a wide hat worn low: not a wound, if you look at it rightly, but a receipt. Proof of the best bargain ever struck.
So if ever you wonder why wise people so often seem to have lost something along the way — a little time, a little ease, a little of the luck that lazier folk keep — now you know the shape of the answer. Wisdom is a well with a keeper, and everyone who truly drinks has paid. The wonderful secret, the one Odin carried home under his grey hat, is that it is worth it. It is always worth it. Close your eyes now — both of them; you may keep both, tonight and always — and sleep, and grow wise slowly, the gentle way, dream by dream.