Maria Popova in Brain Pickings:
Despite his enormous contributions to science,Albert Einstein was no reclusive genius, his ever-eager conversations and correspondence engaging such diverse partners as the Indian philosopher Tagore and a young South African girl who wanted to be a scientist. In 1931, the Institute for Intellectual Cooperation invited the renowned physicist to a cross-disciplinary exchange of ideas about politics and peace with a thinker of his choosing. He selected Sigmund Freud, born on May 6, 1856, whom he had met briefly in 1927 and whose work, despite being skeptical of psychoanalysis, the legendary physicist had come to admire. A series of letters followed, discussing the abstract generalities of human nature and the potential concrete steps for reducing violence in the world. In a twist of irony, the correspondence was only published in 1933 — after Hitler, who would eventually banish both Einstein and Freud into exile, rose to power — in a slim limited-edition pamphlet titled Why War?. Only 2,000 copies of the English translation were printed, most of which were lost during the war. But the gist of the correspondence, which remains surprisingly little-known, is preserved in the 1960 volume Einstein on Peace(public library), featuring a foreword by none other than Bertrand Russell.