A book by Dr. Seuss.
Starts out with fish, and goes on to describe all sorts of wonderful fun (rhyming) nonsense.

My favourite passage is:

Look what we found
in the park
in the dark.
We will take him home.
We will name him Clark.

He will live at our house.
He will grow and grow.
Will our mother like this?
We don't know.

Some other quotes:

Did you ever fly a kite in bed?
Did you ever walk with ten cats on your head?
Do you know how to milk this kind of cow?
We can do it, since we know how.
If you've never done these things, you should.
These things are fun, and fun is good.

There and here, here and there
Funny things are everywhere.

Compare and contrast the first quote to the moral maxims of the bulk of children's literature and you can get an idea of just how revolutionary this book was. As for the second quote...you can understand how useful it is...