A few facts . Correspondence contains 155 messages. It begins with a letter from Heidegger to Jaspers dated April 21, 1920, and ends with a telegram from Gertrude Jaspers on March 2, 1969, sent in response to Heidegger's telegram of condolence on the occasion of Jaspers' death. In 1920-1933. correspondence is quite lively, then, in 1935-36. A few more letters follow, after which the exchange of messages is interrupted for 12 years. 194950. correspondence resumes briefly with the same force, and then fades. It is worth noting that the correspondents carefully stored each other's letters and carefully "set them to work", and Jaspers included even unsent letters here (calculation for historical justice?). The correspondence of the two philosophers was first made public in 1990.[citation needed] It was published by Walter Biemel (on the part of Heidegger) and Hans Zaner (on the part of Jaspers); they, each for their part, provided the text with notes and comments.