In chapter 4, Meg, Charles, and Calvin experience the bizarre feeling of a tesseract for the first time and are miraculously transported to the planet Uriel. The children suddenly find themselves standing in a beautiful field of multi-colored flowers on a pleasant springtime day and are awestruck by the impressive mountain in the background that reaches into the sky. After the Mrs. Ws materialize, Mrs. Whatsit explains to the children that they are currently on Uriel, which is the third planet of the star Malak in the spiral nebula Messier 101. Mrs. Whatsit also explains that they tessered to the planet and informs the children Mr. Murry is in serious danger.
Mrs. Which then prompts Mrs. Whatsit to show her true form by transforming into a beautiful creature that resembles a majestic winged horse. Mrs. Whatsit tells the children to climb on her back and immediately takes flight. As they are flying high above Uriel, the children notice many creatures that resemble Mrs. Whatsit and can hear them making music. When Meg asks what they are singing, Mrs. Whatsit explains that it cannot be translated into human language. Only Charles has the ability to accurately translate the singing, but Meg can feel the resonance of joy emanating through the air by the sound of their music. The singing, roughly translated into human language, is a Biblical verse from Isaiah 42:10. The creatures are singing,
Sing unto the Lord a new song, and his praise from the end of the earth, ye that go down to the sea, and all that is therein; the isles, and the inhabitants thereof ...
The children experience an overwhelming peace and clarity when they hear the music, and Mrs. Whatsit begins to fly higher towards the top of the mountain.