Dr. Seuss wanted to do more than teach kids to read, he wanted to teach them to think critically about serious issues. Wait, isn't that what a liberal arts education is for? (Snap!) In any case, the biggest challenge he came up against was to do this without being "preachy" (source). He wasn't interested in forcing ideas down young throats. In fact, Shmoop once heard him say, "I don't write for children. I write for people" (source). Seuss was interested in making youngsters part of the same serious conversations adults are having.
Applying his signature blend of complex simplicity and outrageous playfulness to serious issues challenges sparkling young intellects and offers entrance to a fantasy word that celebrates imagination and creativity. The Lorax is so much more than an ecological treatise. It's a way for kids to join the conversation about the environment. By treating serious issues seriously—but still playfully—Seuss avoids that preachy tone he so despised.
Easier said than done, right? But Seuss says it and does it:
"I think I can communicate with kids because I don't try to communicate with kids. Ninety percent of the children's books patronize the child and say there's a difference between you and me, so you listen to this story. I, for some reason or another, don't do that. I treat the child as an equal." (Source.)
Well said, Seuss, well said. This sense of equality shines through on every page of The Lorax.