"I think he sets a certain standard, let's say a standard of seriousness. (Q: Doesn't he seem intolerant to you, even merciless?) Sontag: He's very vehement, yes. Kafka too was very vehement, and he excluded a great deal, in his life and in his work. These are people whose lives I find exemplary in some respect-their thoughts, their ideas, their work, their seriousness."
January 1, 1970
https://en.wikiquote.org/wiki/Friedrich_Nietzsche