I recently came across this gem, originally published back in 1969. Here is an excerpt from the book with an important concept behind it: "On Saturday he ate through one piece of chocolate, one ice-cream cone, once slice of Swiss cheese, one slice of salami, one lollipop, one piece of cherry pie, one sausage, one cupcake, and one slice of watermelon. That night he had a stomach ache! (turn page). The next day was Sunday again. The caterpillar ate through one nice green leaf, and after that he felt much better."