In his book, the writer invites schoolchildren to open "thousands of doors" to the world using a universal collection key. The guys will learn about how much an ordinary postage stamp or matchbox can tell, who has traveled around the world for the first time in the world, which means the word "kangaroo" and much more. The world is full of amazing secrets big and small, and the answer to any of them is new Knowledge. Often the key to secrecy can be an ordinary object - a postage stamp or a piece of brick, a newspaper clipping or a match label...