  We exploit four-dimensional tensor identities to give a very simple proof of
the existence of a Lanczos potential for a Weyl tensor in four dimensions with
any signature, and to show that the potential satisfies a simple linear second
order differential equation, e.g., a wave equation in Lorentz signature.
Furthermore, we exploit higher dimensional tensor identities to obtain the
analogous results for (m,m)-forms in 2m dimensions.
