Here’s an extended metaphor, and it’s the best I can do. Say you’re taking a canoe ride on the Ohio River from Cincinnati, Ohio (where I once lived) to Louisville, Kentucky (where I have visited). Distance approximately 100 miles. You know Cincinnati and to a lesser extent your destination, Louisville. You know the larger towns and cities along both banks, and the major tributaries. You intend to get to Louisville, that is, your ending of your novel, and you have certain characters and certain events (those towns and tributaries) in mind. But you have never been on the river. The currents, snags, small islands, smaller tributaries, the drudgery of day to day paddling—the dispiriting drudgery, the innumerable temptations to give up. You know it all in the abstract, but you don’t know what it’s actually like. Everything could change in a day, and Louisville, if you ever reach it, might not bear much resemblance to the city you have in your mind. That combination of the mapped-out and the powerfully and subtly unforeseen is, metaphorically, how I’d describe the writing of a novel.