This book aims to playfully illustrate common and observable truths by making absurd comparisons: "a foot is not a fish." It aims to show that it is not hard to see what is true, and it also tries to establish that, to make sense of our mutual world, agreement about what is true is necessary. What if some of us thought that a foot was a fish? Children understand that while different people have different beliefs and opinions--such as about religion, or what is good to eat--they also understand that beliefs and opinions are not the same as facts, such as what is "night" or "day." Reality cannot be changed by simply saying the opposite of what is true: "we can't just say that red is green." Children also understand that there is a difference between a wish and what is true. They understand, once they are past toddlerhood, that we cannot change the truth just by wishing or hoping: "a wish is just a wish." They know that, although they might wish it to be so, every day cannot be their birthday. Encouraging children to create their own verses (rhyming or not) can be fun, and can further help them in their understanding of what is real and what is not. They undoubtedly will come up with surprising and funny examples of their own.