  We provide a quick proof of the following known result: the Sobolev space
associated with the Euclidean space, endowed with the Euclidean distance and an
arbitrary Radon measure, is Hilbert. Our new approach relies upon the
properties of the Alberti-Marchese decomposability bundle. As a consequence of
our arguments, we also prove that if the Sobolev norm is closable on
compactly-supported smooth functions, then the reference measure is absolutely
continuous with respect to the Lebesgue measure.
