Remark made during a week at Princeton beginning 9 May 1921, later carved above the fireplace of the Common Room of Fine Hall (the Mathematical Institute), Princeton University - in R. W. Clark Einstein (1973) ch. 14
Sarah Josepha Buell Hale, John F. Addington (1859). “A complete dictionary of poetical quotations: comprising the most excellent and appropriate passages in the old British poets; with choice and copious selections from the best modern British and American poets”, p.477