Object lessons: the best of this week's New York auctions

Francis Bacon, Two Studies for a Self-Portrait (1970)Contemporary art evening auction, Sotheby’s, 11 May
Estimate $22m-$30m“People have been dying around me like flies and I’ve had nobody else to paint but myself,” Francis Bacon told the art critic David Sylvester in 1975. Despite Bacon’s increasing tendency towards self-portraiture at the time, Two Studies for a Self-Portrait (1970) is rare: the artist made only two other diptych self-portraits, one of which sold