The hole argument is a story invented by Albert Einstein to set out the difficulties he had in reconciling his principle of covariance with the Mach's principle. Some modern presentations insist that the bare differential manifold loses its physical status and is just an expression of the mathematical framework of the new relativistic theory. In Space-Time-Matter, Hermann Weyl constructed an argument close to the modern hole argument, replacing the hole with a ball of clay. Beside some trivial technical differences, Weyl's (...) argument is original because of the particular concept of mathematics that he inherited from the Gottingen school. (shrink)