"The reader of the four 'Diaries' of Paul Klee.. ..will be initiated – being presumably an outsider – into a mysterious, rare, individual, and watchful world, that of Paul Klee the 'painter'. Indeed, the entries in his diaries were not originally intended for publication, but merely for his own reflection. During his lifetime my father allowed no one, not even myself, access to his most personal confession."
January 1, 1970
https://en.wikiquote.org/wiki/Paul_Klee