“Dreams and Nightmares: Utopian Visions in Modern Art,” curated by Valerie Fletcher, was a very strange exhibit indeed. Conceived in two parts, all the nurturing seemed to have gone to the first, leaving the second to wither and fade. The show offered a survey of art from the first two-thirds of the century, concentrating on work that is either utopian in outlook, or the reverse. Fletcher uses the term “dystopian” to name this latter trend. The etymology is interesting: Sir Thomas More wrote about an ideal society, placing it on an island he chose to call Utopia, from the Greek meaning “no