Subsequently, and following my own (fairly inept) advice, I'm having an evening on my own. Following Max's (usually excellent) advice, albeit partially, I went out.
I walked from the hotel (which is in Arlington, not far from Rosslyn Metro station) across the river into Georgetown, and eastwards along M Street NW towards the city, and when the rain arrived, I dipped into a restaurant for dinner.
I found myself in Fino, an Italian bistro opposite the Barnes and Noble Bookshop, where they furnished me with deep-fried mozarella, garlic bread, and lasagna al forno, with a large glass of Italian medium white wine. It wasn't bad at all, until mid-way through the meal when someone sat down at the baby grand and started to play some jazz. That was bearable, until he was joined by a Bass player. Even so, they were both reasonably ept, I thought, until the bass player stopped slapping the strings and picked up his bow, at which point his performance slipped downhill sharply.
I finished my meal, settled up, and walked back down the street and across the river back into Virginia, and now here I am back at the hotel. Back to my complicated life.
Tomorrow, I'm going back to scarlatti's house, and we're going to try again. We're going to sit down together in front of the screen and read all your comments once more, and see if between the two of us we can get this thing to work. Or, alternatively, spend a day or two not thinking about it and see if we're any closer after that.
Wait and see, watch this space. There is hope -- more than there seemed to be at lunchtime today.