            By 1912, however, Einstein had reached an impasse  , realizing that he needed to go beyond the mathematics that he knew and was familiar with.
<meaning-changed>             By 1912, however, Einstein had reached an impasse  , realizing that he needed to go beyond the mathematics that he knew and was familiar with.
 In the remainder of Einstein's 1911 paper, he discussed the bending of light rays in a gravitational field, but given the incomplete nature of Einstein's theory as it existed at the time, the value that he predicted was half the value that would later be predicted by the full theory of general relativity. (ArXiv version here: arxiv.org/abs/1403.7377.)Ned Wright: Deflection and Delay of Light By 1912, however, Einstein had reached an impasse , realizing that he needed to go beyond the mathematics that he knew and was familiar with.