The poem 'Warning to Children' by Robert Graves encourages children to use their imagination and appreciate the rarity and preciousness of the world around them. It describes a brown paper parcel containing an island with a tree and a fruit, which, when opened, reveals a world of dominoes and blocks of slate. The poem warns against undoing the parcel and getting trapped in the enclosed world, but also encourages children to think about the greatness and muchness of the world they live in.