a rope sailor can moor a large ship simply by wrapping that around a cylinder known as a ca(27, 28]. Note its principle might be relevant to the interaction between DNA and a bacteriophage capsid 29. The second ex- ample is a simple toy known as the Chinese finger trap, where a woven helical braid is loosely wrapped around a finger. The braid tightens and the finger is trapped as it is pulled. The trapping mechanism results from a simple conversion of the traction force to an orthogonal compo- nent, which enhances the load and thus the friction. This type of braid is applicable to sutures in surgery[30), and is also thought to play a role in adhesive proteins[31] Crucial to the geometrical amplification of friction vit interleaved books are the angles 0n that the sheets make as they approach the contact region. It is through these angles that the traction forces result in loads perpen- dicular to the paper-paper interfaces, and thus in large self-created friction forces. This fact is easily verified: one can realise an interleaved-book system with 0,n 0,