According to the first postulate of Special Relativity, all the laws of physics are symmetrical in all inertial frames. So that also means that Maxwell's equations are true in any such frame (experimentally verified). Now we can easily uncouple the four first-order differential equations in free space and that leads to two second order differential equations (in fact six) for the electric and magnetic fields, the wave equations, with the speed of such waves being that of light, which is precisely a constant, depending only on the permitivity and permeability of free-space. So my question is, what is the need of the second postulate if it is easily derivable from the first? It is a radical conclusion, but not an independent assumption, or is it?