Nux's imagination is paradoxically both limited and endless: he's never seen grass, has no idea what it looks like, and the image that's coming to life in his mind is probably absolutely nothing like the truth. She says wires, so he thinks something like green wires, thin and light enough to rustle in the wind but woven together in a loose mat, springy underfoot. He thinks of the sun glittering off it, and thinks it must look very, very shiny, indeed. She says damp earth and he thinks of mud, but... maybe a better mud. Not a sour, sandy mud. A mud where things can grow, like trees with...

"What's leaves?" he asks, caught by the story, even though something in him tells him it's not true. She'd said as much. It's a story; they're making a new faith. She's dismantling Valhalla and putting up something in its place, and if that had been a fiction -- which he's still not sure he can believe -- then so is this.

...But he had seen a tree out there.