'Great picture books are rare. For good reason. To define their qualities, perhaps one could start with what they are not. They are not fashionable, because, while fashions come and go, their appeal remains constant. They are not imitative. They are not literal or prosaic. They are not cynical or clever. Their precise meanings are not easily grasped, but they are always meaningful. They are not easily forgotten.' (Tohby Riddle, 2019)