Nicholson's work on panel paintings with incised lines, such as 'Guitar' [Tate Gallery N05125], led him to the idea of working in full relief. According to the artist his move into relief came about as the result of a happy accident when a chip fell out at the intersection of two lines on one of his panels. The use of relief seems to have provided him with an additional element in the pictorial structure, which enabled him to abandon one of the existing ones, recognisable imagery, and develop a pure abstraction. The white reliefs which followed are remarkable not least for their extremism, which is such that they become emblematic of the ideas of purity and order, expressing an ideal universal beauty. The colour white in particular, with all its associations of health and hygiene, is of central significance in the Modernist tradition stemming from Mondrian and De Stijl which Nicholson's reliefs are part of. In them Nicholson's already extraordinarily refined aestheticism reaches almost spiritual heights. In this work the principal elements are the two circles which are played off against each other, and against the structure of rectangles. Both forms are in turn manipulated within the spatial dimension provided by the relief. This is the 'interplay of forces' which Nicholson has said is central to his abstract art: 'you can create a most exciting tension between these forces'. The 'tension' here comes from the relationship of the circles, particularly their differences, some of which the spectator may only half consciously perceive: for example one is drawn with a compass and one freehand, and one penetrates the layers of relief to a greater depth than the other. The particular effect of cutting circles through layers of a relief is central to these works by Nicholson, as he has made clear: 'You can take a rectangular surface and cut a section of it one plane lower, and then in the higher plane cut a circle deeper than but without touching, the lower plane. One is immediately conscious that the circle has pierced the lower plane without having touched it ... and this creates space. The awareness of this is felt subconsciously and it is useless to approach it intellectually, as this, so far from helping, only acts as a barrier.'
Simon Wilson, Tate Gallery: An Illustrated Companion, Tate Gallery, London, revised edition 1991, p.176