A comforting theme through the Proms season has been late-night Bach. The ordered beauty of the Thuringian composer’s music, the reassuring thought that a human could achieve such perfection, the humble dedication of the day’s creativity to “God Alone the Glory” (Soli Deo Gloria, as Bach signed even secular works) are surely the essence of bedtime prayer. The Goldberg Variations, which András Schiff played on a stage bare except for his spotlit piano, were written with exactly this sleep-preparing purpose as the Radio 3 presenter reminded the assembled multitude.Schiff paused, his hands on the keys, before setting off with the aria on the return journey through 30 variations including repeats, each of which brought a slight intensification of touch. Pausing