Sally O. Lee's Circle and Square is adorable. The text is simple, silly and easy to follow; in other words, perfect for a preschooler. And even with simple, silly text there is a story and a very gentle moral.
The artwork also is (deceptively) simple, silly and easy to follow. The colors are PERFECT for a preschooler. I often let my son dress himself and he has some color combinations that rival those on the pages of this book. The color combinations work on him, and they work in this book. In fact, the artwork is, and exudes, pure joy.