  "It is utterly beyond our power to measure the changes of things by time.
Quite the contrary, time is an abstraction at which we arrive through the
changes of things." Ernst Mach [1].
  What change? Three answers to this are `any change' (Rovelli), 'all change'
(Barbour) and my argument here for the middle ground of a `sufficient totality
of locally relevant change' (STLRC) giving a generalization of the astronomers'
ephemeris time. I then use STLRC as a selection principle on existing and new
approaches to the Problem of Time in Quantum Gravity. Emergent
Jacobi-Barbour-Bertotti time can be interpreted as arising from a STLRC,
resolves the classical Problem of Time and has an emergent semiclassical
counterpart as regards facing the QM Problem of Time.
