A similar relation also holds for classical mechanics, the classical limit of the above, given by the correspondence between Poisson brackets and commutators : [ A , H ] ⟷ ⟷ i ℏ ℏ { A , H } . In classical mechanics, for an A with no explicit time dependence, { A , H } = d A d t , so again the expression for A (t) is the Taylor expansion around t = 0.