Yeats despite the voiced antipathy to ‘abstraction’ is consistently attracted to geometric & quasi-algebraic formulae. One finds it especially, of course, in
a Vision but it is already there in the early occultist activity. The diagram, the conceptual scaffold of reality rather than its vivid immediacy. This can be related to the Modernist tendency towards mathemes, inner structures, the unseen algebra of the sensuous.
The materialisation of the image (Imaginary) is underwritten by a prior geometry or a structure, with the resultant gap between structure and percept which is a signature trope of modernist literature and thought. Increasingly the appearance of the world and its conditions of intelligibility are at variance.