This is the catalogue for a major retrospective organized by SFMOMA and celebrating the work of one of the most important and influential conceptual artists of the century. Sol LeWitt's career has been defined by a series of groundbreaking explorations into the basic building blocks of form and their relationship to philosophical and mathematical concepts. (Some critics have seen his work as visual manifestoes of the ideas of Descartes and Kant.) The fact is, however, that LeWitt's works transform these abstract principles and formulas into objects of beauty and grace, introducing elements of chance, intuition, or irrationality into the scientific systems that inspired their creation. While his thoroughly documented work of the 1960s was firmly fixed in the realm of conceptualism, his turn toward a more lyrical and sensual form of abstraction since then has never received adequate critical attention. This catalogue will chart the evolution of LeWitt's art from the sixties through to the present to show the enormous influence that his delicate balancing act between thought and form, order and disorder, has exerted on younger artists.