Envelopes (2005) by Harriet Russell is delightful. The book brings together the 100+ envelopes she created with different ways of communicating an address, such as mazes, puzzles, illustrations, joining dots, and old maps. As Lynne Truss says in her foreword, “each envelope… is also a triumph of humanity – because... in nearly every case, the letter arrived! Therefore a human person must have worked out Harriet’s code." As the project evolved, the postal workers started writing “Solved by the Glasgow Mail Centre” on the backs of the envelopes, and added their own annotations. It is a work of wit, humour, and faith in the postal system.