" It’s ahead of us. All I can tell you is, not even courage will help.” “Are you reading Alma Mahler again?” “No.” Her voice was even and knowing. The underground river. The ceiling lowers, grows wet, the water rushes into darkness. The air becomes damp and icy, the passage narrows. Light is lost here, sound; the current begins to flow beneath great, impassable slabs. "

― James Salter , Light Years