Did Dr. Seuss write with hidden messages?

Not exactly hidden — Theodor Seuss Geisel was extremely direct in interviews about what his books were about. But the allegorical layer is below the surface of the whimsy in ways that children receive emotionally rather than analytically.

What is The Lorax actually about?

Industrial capitalism's destruction of the natural environment. The Once-ler represents unregulated industry; the Truffula trees represent natural resources; the Lorax speaks for the ecosystem. The book ends with a single Truffula seed and the instruction to plant it and care for it. It was published in 1971, at the dawn of the environmental movement.

What is The Butter Battle Book about?

Nuclear arms race and mutually assured destruction. The Yooks and Zooks fight a generations-long war over which side of bread to butter. Both sides develop increasingly destructive weapons until both hold "bitsy big-boy boomeroos" over the other's city. The book ends unresolved — both characters preparing to drop their weapons simultaneously. No lesson is offered; the situation is presented as the absurdity it is.

What is Yertle the Turtle about?

Fascism and authoritarianism. Yertle the Turtle keeps building his throne higher on the backs of other turtles. He declares himself ruler of all he can see. Mack — the turtle on the bottom — burps, the stack collapses, and Yertle falls into the mud. Geisel explicitly said Yertle was Hitler.

What is The Sneetches about?

Racism and the absurdity of discrimination. Star-bellied Sneetches discriminate against plain-bellied ones. Sylvester McMonkey McBean's machine adds and removes stars until no one can remember who was who originally — demonstrating that the discriminatory categories were always meaningless.