  For a long time it is believed that black hole horizon are thermal and
quantum mechanical in nature. The microscopic origin of this thermality is the
main question behind our present investigation, which reveals possible
importance of near horizon symmetry. It is this symmetry which is assumed to be
spontaneously broken by the background spacetime, generates the associated
Goldstone modes. In this paper we construct a suitable classical action for
those Goldstone modes, and show that all the momentum modes experience nearly
the same inverted harmonic potential, leading to an instability. Thanks to the
recent conjectures on the chaos and thermal quantum system, particularly in the
context of an inverted harmonic oscillator system. Going into the quantum
regime, the system of large number of Goldstone modes with the aforementioned
instability is shown to be inherently thermal. Interestingly the temperature of
the system also turns out to be proportional to that of the well known horizon
temperature. Therefore, we hope our present study can illuminate an intimate
connection between the horizon symmetries and the associated Goldstone modes as
a possible mechanism of the microscopic origin of the horizon thermality.
