Admittedly, momentum requires a certain tunnel vision. This is one of the dirtiest of the dirty little secrets about writing. Everything about history and life itself is potentially infinite (except one’s life span, unfortunately). There is always another document that could have been consulted, just as there is always another fact about a friend or partner that if you knew would make you understand her or him better. But life is short and if you want to write more than a dissertation or one book or two books and so on, you have to limit yourself to what can be done in a certain time frame. You cannot accumulate pages if you constantly second guess yourself. You have to second guess yourself just enough to make constant revision productive and not debilitating. You have to believe that clarity is going to come, not all at once, and certainly not before you write, but eventually, if you work at it hard enough, it will come. Thought does emerge f