Bertrand Russell had been jailed for his anti-war activities but his close intellectual friend Ludwig Wittgenstein was in the Austrian army as a private soldier. By March 1919 Russell had been released but Wittgenstein was still in a prisoner of war camp in Italy. He wrote to Russell in German about philosophy. The bizarre scenario was of an imprisoned enemy soldier writing to a convicted anti-war activist. Wittgenstein also wrote to John Maynard Keynes who was one of the British negotiators at the Versailles Peace Treaty, also in German. The world was a very different place for the European elite who shared a common social and intellectual environment.
Ray Monk Bertrand Russell: the spirit of solitude p 548