Mass–energy equivalence arose originally from special relativity as a paradox described by Henri Poincaré. Einstein was the first to propose that the equivalence of mass and energy is a general principle and a consequence of the symmetries of space and time. The principle first appeared in the paper "Does the inertia of a body depend upon its energy-content?", one of his "Annus Mirabilis" (Miraculous Year) papers, published on 21 November 1905. The formula and its relationship to momentum, as described by the energy–momentum relation were subsequently developed in a series of advances over the next several years.