The Malcontents by C.P. Snow

As Stephen woke, the single bell was ringing. He didn't wake, as he had sometimes done, into well-being and then become invaded by disquiet: the strain of the night before had ceased, just as when he was walking with his friends. It was like a morning in childhood, the room still dark, no need to get up yet. The bell clanged on, it must be for the early communion, eight o'clock, the communion to which his father went.

It was luxurious, lying in the familiar room, half-awake. An idea about his work entered into consciousness. Neutrons packed together. No, the equations wouldn't fit.