  In this lecture, intended for a general audience, I describe Schr\"odinger's
thought experiment which was designed to show the strange results of extending
the formalism of quantum theory, particularly the idea of superposition, beyond
the subatomic regime. I describe a way to understand superposition in the terms
of formal logic. I trace the development of Schrodinger's ideas after this
thought experiment, and briefly sketch some work which realises it in actual
experiments, and proposals for taking it further.
