[after the Once-ler has finished his story]

So, this is really all your fault. You destroyed everything.

[ashamed]

Yes. And each day since the Lorax left, I've sat here, regretting everything I've done. Staring at that word, "unless," a-and wondering what it meant. But now I'm thinking... Well, maybe you're the reason why the Lorax left that word there.

[shocked]

Me? Why would he leave that for me?

Because unless someone like you cares a whole awful lot, nothing's going to get better. It's not. [sticks his arm out the window and drops a single seed, which Ted catches] The last Truffula seed. You need to plant it, Ted.

Yeah, but... nobody cares about trees anymore!

Then make them care! Plant the seed in the middle of town where everyone can see! Change the way things are. I know it may seem small and insignificant, but it's not what it is. It's about what it can become. That's not just a seed... anymore than you're just a boy.

[Ted takes the seed and gets on his scooter]

I won't let you down! [drives back to Thneedville]

I know.