James Fenton at the Guardian on the relationship between writing and personal experience:
"I read your poem," said a friend some years ago, pausing before adding solicitously: "Are you all right?" The answer is almost always in my view "Yes". However depressing the content of the poem, if you've managed to write one, and get it published, then you are going to be in a good mood (at the very least about that one important thing). So it is that a last line, expressing the deepest spirit of depression, may be written in a mood of complete professional elation.
What's going on is a simultaneous introspection (supposing the poem to be based on one's own, as opposed to someone else's, feelings) and purposeful tinkering. If the feeling described is one of depression, it cannot logically be experienced to the point of paralysis in the act of composition. There must be some kind of excitement of the faculties, some spirit egging us on, saying "That's good! ... No, that's not it ... That's got it precisely."
This must be the case even for a writer like Paul Celan, in those moments when he is putting the words down on paper. It must have been the case (to take another suicide) for Sylvia Plath when she was writing "Daddy" - indeed, you may feel that you can hear that triumph in the poem itself. It carries its own sense of an extraordinary feat pulled off - a sense that perhaps runs counter to the ostensible meaning of the poem.
That seems to me extraordinarily apt--"complete professional elation"--one of the strongest feelings known to mankind....