  This paper concerns what Background Independence itself is (as opposed to
some particular physical theory that is background independent). The notions
presented mostly arose from a layer-by-layer analysis of the facets of the
Problem of Time in Quantum Gravity. Part of this coincides with two relational
postulates which are thus identified as classical precursors of two of the
facets of the Problem of Time. These are furthemore tied to the forms of each
of the GR Hamiltonian and momentum constraints. Other aspects of Background
Independence include the algebraic closure of these constraints, expressing
physics in terms of beables, foliation independence as implemented by
refoliation invariance, the reconstruction of spacetime from space. The final
picture is that Background Independence - a philosophically desirable and
physically implementable feature for a theory to have - has the facets of the
Problem of Time among its consequences. Thus these arise naturally and are
problems to be resolved, as opposed to avoided `by making one's physics
background-dependent in order not to have these problems'. This serves as a
selection criterion that limits the use of a number of model arenas and
physical theories.
