Your manifesto should answer these questions (among others):
- What is the purpose of literature?
- What is my individual purpose within that larger purpose?
- Why do I write?
- Whom do I write for and why?
- What is my ultimate goal as a writer?
Ulterior motiveThis isn't your normal fiction-writing prompt, and calling my motive "ulterior" isn't exactly accurate. But, hey, I've already created the template for these things.
The point is for you to think about your writing on a larger landscape. It can only help you, in the long run, to have some clear understanding of what you hope to do with your writing, and whom you write for.
Putting it all down in words seems a natural step. You know, for a writer.