How did Einstein overthrow Newtonian physics?

Newton believed in the absolute state of things, that time and space were constants which needed only to be observed, measured, and quantified. Einstein, theorizing several centuries later than Netwon, took Netwonian physics and turned it on its head by erting (and later proving) that space, gravity and time were, in fact, relative and not constant forces in the universe. Einsten related energy, m, and the speed of light in a way (e=mc^2) that overthrew the notions held by his predecessors.