  General (tele)parallel Relativity, G$_\parallel$R, is the relativistic
completion of Einstein's theories of gravity. The focus of this article is the
derivation of the homogeneous and isotropic solution in G$_\parallel$R. The
first-principles derivation, based on a non-trivial realisation of the
symmetry, supersedes and unifies previous constructions of Riemannian and
teleparallel cosmologies, and establishes the uniqueness of the physical
solution. The constitutive law and the form of the material and inertial source
currents is presented in the tensor (Palatini) formalism and adapted to the
cosmological background, which exhibits novel features absent in the previously
studied, static solutions to the theory. The results are contrasted with those
in some incomplete theories, such as sitting at the three corners of the
geometrical trinity and corresponding to particular reference frames in
G$_\parallel$R.
