We are taught that adding a catalyst to an equilibrium system does not alter the position, just the rate of equilibrium attainment, because it increases the forward and backward rate by the same amount. Why and how can that be? The activation energies will be different for the forward and backward direction. Does a change in forward/backward pre-exponential factors somehow exactly cancel the difference in Ea? Seems hard to believe. Or is it some outcome from the Boltzmann distribution curve? Or some other reason??!!