The Time Machine

None visible above ground. The Morlocks maintain machinery in the dark, for reasons nobody remembers.

The Eloi do nothing whatsoever. They eat fruit, play in the river, decorate themselves and each other, and forget anything that happens after a few hours. Below them the Morlocks keep the machines running, and eat the Eloi.

Enforced idleness — Everything is provided, so nothing is left to do — and that turns out to be unbearable.

The origin of the shape every later work inherits: a leisured class above, a working class below, and the discovery that the arrangement runs in the opposite direction to the one it appears to.