Black hole: Gravitational charge equal to field energy

In general relativity, both non-gravitational matter energy as well as grav itational field energy are sources of the field. In this note we propose th at a collapsing body turns into a black hole when contributions of matter e nergy and field energy become equal, For measure of field energy we use the Brown-York quasilocal energy while for the gravitational charge (measure o f gravitational pull matter energy produces), the Gauss-Komar integral. Thi s is an energetics definition, similar to the classical escape velocity arg ument, which is intuitively and physically appealing. One of the remarkable results that immediately follows is that an extremal hole can never be for med by collapse of a dispersed state as there is no net energy to drive it. This is however well-known from other considerations, but here it follows from simple energetics of collapse.