He was a conceptual artist with a very beguiling concept. The late Sol LeWitt's wall drawings are based on instructions devised by him but carried out by others. It may not sound like a formula for fun, but LeWitt proved that even Conceptualism could be luscious, that the most parsimonious and disembodied of artistic practices could be a means to arrive at a whole fund of sensual pleasures. This fall, MASS MoCA, the spacious art space in North Adams, Mass., opens a gorgeous installation of 100 of the drawings that will stay on view for 25 years. In effect, what they're producing will be a one-man LeWitt museum, with the advantage that it's part of the huge contemporary art center that is MASS MoCA, which will keep LeWitt's work in a constant dialogue with other art.