 However, in this section, we wish to present a rather simplified version of just one of Einstein’s derivations, published in 1946 (Einstein 1946). We will follow closely the simplified version of Einstein’s 1946 derivation developed by Ralph Baierlein (1991), who has used his derivation to teach Einstein’s equation to undergraduates who are not science majors. John Norton has used essentially the same simplified derivation in the Cambridge Companion to Einstein (Norton 2014). 