translation.en: But Einstein realized that Newton had left something out of the story, because even Newton had written that although he understood how to calculate the effect of gravity, he'd been unable to figure out how it really works.
translation.zh: 但是“爱因斯坦”意识到“牛顿”遗留下了一些未解的东西， 甚至“牛顿”本人也提到 虽然他明白如何计算“重力”的影响， 但是他无法真切地了解“重力”究竟是如何工作的。