Whether you're at your desk or not when a poem's under way, isn't three that constant eddy in your mind? If it's strong enough all sorts of random flotsam gets drawn into it, how selectively it's hopeless to decide at the time. I try to break off, get away from the page, into the kitchen for a spell of mixing and marinating which gives the words a chance to sort themselves out behind my back. But three's really no escape, except perhaps the third drink.