'Four-Piece Composition' is an extreme manifestation of Moore's interest, at this time and later, in the idea of splitting the human figure into parts. He did this partly in pursuit of one of the fundamental principles of his art which, in his statement in Unit One in 1934, he defined under the heading 'Full three dimensional realisation.' For Moore. since sculpture is by its very nature three-dimensional, then it became a matter of philosophical principle to be as truthful to that nature as possible. Beyond that, fully utilising every aspect of the sculpture increases the artist's scope for expression, and actually breaking the forms apart creates a further and dramatic enrichment of the work through the changing relationships of the parts as the spectator moves around it. Later, Moore also commented 'I realised what an advantage a separated two-piece composition could have in relating figures to landscape. Knees and breasts are mountains. Once these two parts become separated you don't expect it to be a naturalistic figure: therefore you can justifiably make it like a landscape or a rock.'
Here the arched form, which is in fact the left leg of the figure, with bent knee, is strongly suggestive of an arched cliff formation. The boomerang shape, the artist has said, represents a mixture of body and leg, the leg being conceived as resting flat on the ground bent at the knee. The large upright form is the head and top part of the body, indeed Moore said, it is 'nearly a body in itself'. The curved shape carved out of the top of this element was introduced to counteract the excessive simplicity and abstractness of the form but also has the implication of a mouth. The small pebble-shaped element is the umbilicus, or belly button, an important symbol to Moore, representing the connection of one life to another and by extension the whole process of procreation. The circle penetrated by a line incised on the boomerang form could be another umbilicus, the artist has said, and to the outside observer it may also suggest an image of fertilisation, just as the mouth may appear to be open in an orgasmic cry. These incised lines, and those on the head form, are not intended to have hard and fast readings as body elements, although the circle on the head could be an eye. The lines are there to activate and emphasise the surface of the sculpture, which for Moore was particularly important in this case because of the smoothness and translucency of the stone, Cumberland alabaster, from which it is made. However, people's enthusiasm for the natural beauty of Moore's Cumberland alabaster carvings was such that he later gave up using it, feeling that the response to the material was interfering with the significance of the sculpture.
Simon Wilson, Tate Gallery: An Illustrated Companion, Tate Gallery, London, revised edition 1991, p.179