As Seuss's very earliest children's book, And to Think That I Saw It on Mulberry Street is full of very basic illustrations that set the stage for later works. He isn't using any of his wacky anthropomorphic animals yet (Cat in the Hat, we're talking to you), but he's setting the stage for them with animals and people sporting the usual goofy and friendly Seuss expressions. There's also a pretty serious use of white space—most of the page is dedicated to the text.

The Good Stuff:

A Blank Slate

The whiteness of the page mirrors Marco's imagination. At the very beginning when we see him walking home from school, there's not much on the page except a very little Marco. When he sees the horse and wagon, it's similarly small and swamped by the rest of the page, which is nothingness.

However, as Marco's imagination begins to take off, the pictures get bigger and more complex. As the blank slate of his mind starts filling up with fantastical things, we start getting more illustrations. The reindeer and sleigh take up more of the page, and then the elephant and Rajah, and then the brass band… until finally we have a page chock-full of all sorts of zany characters, from the Mayor to an airplane to a brigade of police.

At the end when Marco's dad asks him what he saw, though, everything gets smaller again. We just see Marco and the horse and wagon, because all the imaginary elements had to be taken away in order to fit into his dad's version of reality (psst… more on this over in the "Themes" section).

Primarily Colorful

Seuss uses bright colors in And to Think That I Saw it on Mulberry Street, but he sticks to a very simple palette, using bold bright colors like red, yellow, blue, and green. There isn't much shading, and the drawing look like they've been dropped straight from a child's imagination. Seuss keeps his illustrations simple yet zany, and this is a thread that follows through to his later works as well.

People Going Places

This is one of the Seuss books in which we see a whole lot of people, as opposed to a whole lot of anthropomorphic animals and creatures. Marco's imagination conjures up all sorts of groups: a brass band, a police brigade, a Rajah riding an elephant, and even the Mayor himself. Seuss is still working off of standard ideas of illustrations in a children's book at this point, though he keeps it full of different, interesting people with the occasional animals who don't wear hats or talk. In other words, he's pushing the mold, but he hasn't quite broken it yet.