My aim here was to focus on the effects of placing much of the picture's subject matter in deep shadow. The jug, glass of water and green grapes are all shaded by an unseen curtain to the left. Although we mainly see the dark backcloth through the jug, the glass surface does reflect to a small extent. On close inspection the studio and its contents (including me) can be made out dimly. (http://galtonfineart.com/jeremygalton/)