I love this quote from Aaron Sorkin, about writing a film about Steve Jobs:
"If I can end the movie with that text, with that voiceover - 'here's to the crazy ones' - if I can earn that ending then I'll have written the movie I want to write."
I like how he is setting out to "earn" an ending. It sounds as if he is yet to write it or is in the middle of it, but I love that the ending, the thematic significance of the film, is what he has uppermost in his mind, and what he is aiming for. He wants the film to end in a certain way and to say something, not just follow a character in the course of a conflict, as so many screenwriting books exhort writers to do.
I am midway through a second draft of my novel, and also have an ending in mind I hope I can achieve. It's possible it might change, and you must always leave yourself open to that possibility, but I would be disappointed if my story did not make it.
In my beginning is my end, said Toilets in 'East Coker'. It is also true that you cannot really write the beginning of a story without knowing how it ends. The beginning of my story coils and flips in my head like a fish in a deep fat fryer the further away I get from it. When I finish the ending I shall need to go back to the beginning and rewrite it.