The first wall drawings originated with LeWitt's participation in the "Xerox Book" project curated by Seth Siegelaub. With this project, the conditions of artistic production were standardized and the artists were given a series of "requirements" they were asked to follow. LeWitt's entry consisted of 24 variations of a line drawing, two of which were shown at Paula Cooper Gallery in 1968 as large-scale reproductions in pencil. LeWitt effectively freed line from its traditional roles and functions of describing contour, constructing space (as an orthogonal), and acting as the expressive signature of an artist's intention or "genius." Representing a critical development in his work, the wall pieces focused on the overall concept and the rules of execution rather than the work itself, which would inevitably be painted over. These qualities, arguably the absolute "basics," are also evident in another notorious work of the same year, Buried Cube Containing an Object of Importance but Little Value, documented only in impersonal photographs. LeWitt later used photography to supplement a number of other projects including his autobiography, a collection of 124 photographs published in book form. LeWitt himself is rarely featured in these pictures; he most often refused to submit pictures of himself for publications, insisting that the focus should be on his work and not himself.