Symbolism, Imagery, Allegory
Wait a minute. Green Eggs and Ham is supposed to promote reading, right? So, why the anti-reading message? The big guy is just trying to read his newspaper when Sam starts with the weird food. Right away, Sam wins. The big guy forgets all about his paper and becomes a green eggs and ham junkie. So, what's the message here? "Make food, not books"?
Probably not. Let's take a look from another angle.
It's not the newspaper itself that's meaningful, it's the way the big guy is reading it: with a sour look on his face, totally isolated from others. What does he think he is, a PhD student? Or a totally disinterested dad at the breakfast table? The newspaper here symbolizes reading as a boring, solitary activity performed by boring, solitary people.
When we bring Sam's signs into the mix, things get even more interesting.
The first one, of course, says "I am Sam" (1), and the second one says, "Sam I am" (3). Sam seems to be saying, "Hey, don't read that boring paper! Spend time with me! Read me!" On the second sign, the letters are bright, attention-getting red. Maybe Sam just wants some QT with the big guy.
In Green Eggs and Ham, the newspaper is isolating reading material. Sam's signs, on the other hand, are interactive reading material, intended to forge a connection with another person. Dr. Seuss is shouting at us: Reading is fun! Reading is active! Reading is a way to connect with others! To that we say amen.