We show how one can be led from considerations of quantum steering to Bell's
theorem. We begin with Einstein's demonstration that, assuming local realism,
quantum states must be in a many-to-one ("incomplete") relationship with the
real physical states of the system. We then consider some simple constraints
that local realism imposes on any such incomplete model of physical reality,
and show they are not satisfiable. In particular, we present a very simple
demonstration for the absence of a local hidden variable incomplete description
of nature by steering to two ensembles, one of which contains a pair of
non-orthogonal states. Historically this is not how Bell's theorem arose -
there are slight and subtle differences in the arguments - but it could have
been.Comment: Minor changes to v1, new footnote [8] and reference [19] adde
