“Adults are only obsolete children.”

“Every once in a while, I get mad. 'The Lorax' came out of my being angry. The ecology books I'd read were dull... In 'The Lorax,' I was out to attack what I think are evil things and let the chips fall where they might.”

“Once-ler! You're making such smogulous smoke - my poor swomee swans, why they can't sing a note! No one can sing who has smog in his throat.”

“You ought to be thankful a hole heaping lot, for The places and people you're lucky you're not!”

“Plant a new Truffula. Treat it with care. Give it clean water. And feed it fresh air.”

“The mind is a finer body, and resumes its functions of feeding, digesting, absorbing, excluding, and generating, in a new and ethereal element. Here, in the brain, is all the process of alimentation repeated, in the acquiring, comparing, digesting, and assimilating of experience. Here again is the mystery of generation repeated.”

“You know you've got to exercise your brain just like your muscles.”

“As the brain-changes are continuous, so do all these consciousnesses melt into each other like dissolving views. Properly they are but one protracted consciousness, one unbroken stream.”