The Lorax

A boy visits the Once-ler, a reclusive figure living behind a rusted, extra-thick, super-duper glass barrier in a bleak, treeless town.

For a price, the Once-ler tells the story of how he arrived in a valley of Truffula Trees, invented the multi-purpose Thneed, and began chopping down the trees to make more — despite the repeated warnings of the Lorax, a small orange creature who "speaks for the trees" and for the animals who depend on them: the Brown Bar-ba-loots, the Swomee-Swans, and the Humming-Fish.

As the Once-ler's factory grows, the forest is destroyed, the animals are driven away, and the last tree falls. The Lorax vanishes, leaving behind a single word carved in stone: "UNLESS."

Published by Dr. Seuss in 1971, The Lorax is one of the most influential environmental fables ever written for children, and it ends with the Once-ler passing the last Truffula seed to the boy, urging him to plant it and let the forest — and the Lorax — return.