"Now, don't be frightened, loves," Mrs. Whatsit said. Her plump little body began to shimmer, to quiver, to shift. The wild colors of her clothes became muted, whitened. The pudding-bag shape stretched, lengthened, merged. And suddenly before the children was a creature more beautiful than any Meg had even imagined, and the beauty lay in far more than the outward description. Outwardly Mrs. Whatsit was surely no longer a Mrs. Whatsit. She was a marble-white body with powerful flanks, something like a horse but at the same time completely unlike a horse, for from the magnificently modeled back sprang a nobly formed torso, arms, and a head resembling a man's, but a man with a perfection of dignity and virtue, an exaltation of joy such as Meg had never before seen. No, she thought, it's not like a Greek centaur. Not in the least.
From the shoulders slowly a pair of wings unfolded, wings made of rainbows, of light upon water, of poetry.
Calvin fell to his knees.
"No," Mrs. Whatsit said, though her voice was not Mrs. Whatsit's voice. "Not to me, Calvin. Never to me. Stand up."
"Ccarrry themm," Mrs. Which commanded.
With a gesture both delicate and strong Mrs. Whatsit knelt in front of the children, stretching her wings wide and holding them steady, but quivering. "Onto my back, now," the new voice said.
The children took hesitant steps toward the beautiful creature.
From the Paperback edition.