Sol LeWitt, Five Modular Structures, 1972.
"…dis-satisfied with the surface of the large, slab-like minimalist pieceshe had been making in wood, which did not give him the industrial look he wanted, he stripped the ‘skin’ of the piece away to reveal the skeleton beneath. This step re-defined his relationship to space. Unlike other Minimalists, who Lucy Lippard described as occupying, denying, dispersing and conquering space, LeWitt incorporated it. Interior space became the focus of his work, in permutations of open and closed geometrical serial forms - always in white, to obliterate any possibility of expressiveness.”
(Chrissie Illes, 1993, Sol LeWitt Structures 1962-1993. The Museum of Modern Art: Oxford. pp.11)