The speaker is looking out from a plane, above the clouds, and finds it easier to believe in something greater than himself. A patch of light falls on the white cloud tops below, and he watches it calmly, letting his eyes rest on its faded blue center instead of straining toward it. He asks who would question what can't be known, as if the view itself makes doubt feel unnecessary.
Then the poem turns to the friend named in the title. The speaker remembers George's snow-white hair, now ash, and admits he can't explain why or how it changed so suddenly. The last line brings it home: he doesn't know when he will follow. The mood is quiet and reflective, with a gentle acceptance that carries an undertone of grief and worry about mortality. The calm of the sky sits beside the sadness of loss, and the poem never claims to resolve either one.