"Green Eggs and Ham" is a book written to be read aloud to preliterate children. And new research--by economists such as James Heckman, and others--now reveals that a child's intellectual and civic development is often made (or marred) by the stimuli he receives well before he learns to read. So a book that electrifies a child when read aloud is not merely a source of pleasure, but a building block for his future.
"Green Eggs and Ham" is a very American book, of course, but good children's literature has certain universal characteristics. Plainly, a book must be fun. It cannot be a snooze (although sleep by the end of it is a parent's delight). So the language is paramount: If it is alluring, a child's imagination is captured; if it is all flat, the audience is lost. The pictures can be as important as the language, although great art can never rescue a flaccid text.
A good children's book, moreover, must provoke a desire to return, to be read to from the same pages again and again. For this, it must have an "aftertaste." This may either be a lesson that is left in the young mind, or a deposit of fuel for the imagination, in the form of a character, or a twist in the tale, or a rhyme that, like a good tune, insinuates itself into a child's brain. "Green Eggs and Ham" has all of these.
It is also fine, and often part of the fun, that the child be disconcerted by what has just been read to him. So darkness in a tale is no bad thing. Here, however--and especially where being disconcerted shades into being disturbed--it is important that the book end well, and on a comforting note, with a restoration of the natural order.
"Green Eggs and Ham" is usually my gift to my friens upon the birth of their first child. Reading it is an important part of growing up.