ODIN

Once upon a time and long ago, Odin was walking under the branches of Yggdrasil when two ravens swooped down and settled upon his shoulders. The raven on his left was white as the mists of Niflheim (for back then, all ravens were white), and his eyes mirrored the clouds. The raven on his right glistened in the sun like the snows of Jotunheim, and looked at him with bright clear eyes. And Odin called the raven to his right Hugin, which is Thought, and the other one he named Munin, which means Memory.
As the days passed, Hugin and Munin matched the Allfather’s curiosity for everything in the Nine Worlds, flying around and watching and listening to whatever they could, and in the evenings, they returned to him to tell him all they had seen and heard in the long hours of the day. They told him about the slow thoughts of the mountains, the colorful and ever-changing memories of men, and the sound of the song in the heart of everything that lives. And though Odin delighted in the knowledge they brought, he always felt they had missed something, and he said, “That was much, but not yet enough. Tomorrow you must fly again. Try to rest now.” And the ravens slept uneasily, not knowing what they had missed, and every morning, they flew out again.
There came one of many evenings after another long day when they had once again seen all that Sunna’s shine could show, had listened to all men’s bright thoughts in Midgard, and read their waking memories, when Hugin said to Munin, “We cannot return yet. It is not enough. We must go farther.” And they flew on into the night.
And Hugin flew through the dark dreams of mankind and heard their thoughts which they dared not think during the daytime, not even before themselves. He winged through the black void between the stars where there was nothing at all, and on to the twilight world of the future, where there is equally nothing and everything at once. And when he returned, his feathers, from tip to tip, were black as the night.
And Munin flew through the minds of men into the shady corners and cellars where they had hidden all the things they did not like, and locked them away, saying “I do not remember.” He soared through the sightless void of Ginnungagap, and on and on until he arrived at the ashes of Ragnarok which obscured this age from the next. And when he returned, his feathers, from beak to tail, were as black as soot.
The ravens returned to Odin just before the break of morning, when the night is at its darkest, and when they settled back on his shoulders, he knew all that they had seen, and they did not need to tell. And he understood what had been missing, and nodded, and said, “It is much, and it is enough. For tonight. You may rest.” And the ravens blinked drowsily into the first rays of the rising sun which glinted on their now black feathers, tucked their beaks under their wings, and slept very well.
Since that time, all ravens have been seen to be as black as a shadow on a starless night. Very rarely it happens that somebody catches a glimpse of a white raven, and should you ever be lucky enough to see one, you’ll know that you have wandered far off and back into the land of memory, before ravens came to be black.