Writing is mind traveling – destination unknown.
This quote comes from a book I picked up at the thrift store. Write Source 2000: A Guide to Writing, Thinking and Learning. Written by Patrick Sebranek, Verne Meyer, and Dave Kemper.
In a practical sense this isn’t true. When you write you do have an idea of where you are going with it, a purpose, a goal. However, there are always going to be surprises along the way, new information comes along, a better idea than your original plan or a change in your life which alters your perspective and so on. As you begin to put your ideas into form (versus floating around in your head and the notes you may have from research) the writing begins to take shape. It seldom ever works out exactly the way you thought it would. It evolves. Like a living thing, the writing evolves and becomes something more. Final destination is never a fixed point, not until the very last time you proofread your copy.