" Holston lifted an old boot to an old step, pressed down, and did it again. He lost himself in what the untold years had done, the ablation of molecules and lives, layers and layers ground to fine dust. And he thought, not for the first time, that neither life nor staircase had been meant for such an existence. The tight confines of that long spiral, threading "

― Hugh Howey , Wool Omnibus (Silo, #1)