The creatures - In the book, there are many depictions of doubts. These doubts are generally colourful creatures that resemble in some way the question that originates them, such as "how fishes breath underwater?", "how the stars keep shining?" or "how do the planets hang in the sky?". The doubts that come from adults, however, look more abstract and less colourful. They are inspired by the work of Joan Miró mostly.