There’s something else going on – an asceticism, but in a novel form. If Beckett suffered from depression, he was able to make it an instrument better than most. Which reminds me of George Steiner’s thought that Proust and Dostoevsky were artists who used their own illnesses as great perceptive instruments. It’s in Beckett’s rejections (that we start to see in the first volume of letters), for instance going from a positive to a negative on Jane Austen, that we start to see something like depression become a true instrument.
— From a comment here