He began to develop his own form of constructed sculpture in Norway, and 'Head No.2' is a later enlargement by the artist of one of his most striking works of this period. Not completely abstract, it has a strong human presence, but is constructed according to the principle of stereometry which was fundamental to Gabo's later fully abstract work. The essence of stereometric construction is that it enables the artist to define form in terms of space, rather than mass. In his essay Sculpture: Carving and Construction in Space published in 1937, Gabo wrote 'Up to now sculptors have preferred the mass and neglected or paid little attention to such an important component of mass as space ... we consider it as an absolute sculptural element. I do not hesitate to affirm that the perception of space is a primary natural sense which belongs to the basic senses of our psychology.' This last remark is very significant since human beings are powerfully affected by the nature and structure of the spaces around them, for example the feelings we have on walking into a great cathedral or, on the other hand, being squashed in a crowded tube train.
Gabo's personal theory of abstraction is continued in his Realistic Manifesto, published to accompany an exhibition of his work in Moscow, in 1920. The title was deceptive, as Gabo later explained: 'We all labelled ourselves constructors - the word realism was used by all of us because we were convinced that what we were doing represented a new reality.'
Abstract artists tend to use the term realism to stress that their work has its own independent existence, that it is a new creation, in no way an imitation of some other thing. In the Realistic Manifesto Gabo wrote: 'the realisation of our perceptions of the world in forms of space and time is the only aim of our art ... We construct our work as the universe constructs its own, as the engineer constructs his bridges ... in creating things we take away all that is accidental and local leaving only the constant rhythm of the forces in them'.
Gabo took an important step in his search for an art of pure space when he adopted the use of transparent plastics and glass, and one of his first mature masterpieces is 'Column', the first model for which, made in 1920-1, is in the Tate Gallery collection [T02167]. As Gabo explained, it is a kind of abstract architecture: 'From the very beginning of the Constructivist Movement it was clear to me that a constructed sculpture, by its very method and technique brings sculpture very near to architecture ... My works of this time up to 1924 ... are all in the search for an image which would fuse the sculptural element with the architectural element in one unit. I consider this Column the culmination of that search.'
Simon Wilson, Tate Gallery: An Illustrated Companion, Tate Gallery, London, revised edition 1991, p.146