Conceptual art also reacted against the commodification of art; it attempted a subversion of the gallery or museum as the location and determiner of art, and the art market as the owner and distributor of art. Lawrence Weiner said: "Once you know about a work of mine you own it. There's no way I can climb inside somebody's head and remove it." Many conceptual artists' work can therefore only be known about through documentation which is manifested by it, e.g. photographs, written texts or displayed objects, which some might argue are not in themselves the art. It is sometimes (as in the work of Robert Barry, Yoko Ono, and Weiner himself) reduced to a set of written instructions describing a work, but stopping short of actually making it—emphasising the idea as more important than the artifact. This reveals an explicit preference for the "art" side of the ostensible dichotomy between art and craft, where art, unlike craft, takes place within and engages historical discourse: for example, Ono's "written instructions" make more sense alongside other conceptual art of the time.