  In this paper we introduce a definition of time that emerges in terms of the
geometry of the configuration space of a dynamical system. We illustrate this,
using the Hamilton-Jacobi equation, in various examples: particle mechanics on
a fixed energy surface; non-Abelian gauge theories for compact semi-simple Lie
groups where the Gauss law presents new features; and General Relativity in
$d+1$ dimensions with $d$ the dimension of space. The discussion in General
Relativity is like the non-abelian gauge theory case except for the
indefiniteness of the de Witt metric in the Einstein-Hamilton-Jacobi equation,
which we discuss in some detail. We illustrate the general formula for the
emergent time in various examples including de Sitter spacetime and
asymptotically AdS spacetimes.
