The philosopher whom Einstein admired most was Baruch (later, Benedictus) Spinoza, the seventeenth-century Jewish philosopher, who was excommunicated by the Amsterdam synagogue and declined the Heidelberg professorship in order to live as a lens grinder, leading an independent life dedicated to philosophical reflections.... Einstein was most influenced by Spinoza's thesis of an unrestricted determinism and the belief in the existence of a superior intelligence that reveals itself in the harmony and beauty of nature.


Baruch Spinoza

The earliest recorded reference of Einstein to Spinoza is a poem from 1920. We are not used to think of Einstein as a poet, and one may wonder what triggered his poetic expression in that year. Here I offer a speculation, based on an unexpected discovery made during a recent visit to a little house in the village of Rijnsburg, just outside Leiden.