Rhythm

Roinan Jakobson drew our attention to grammatical features in poetry. He compared the role of pure grammatical parallelism in poetry to geometrical features in painting. ‘For the figurative arts’ he wrote, ‘geometrical principles represent a “beautiful necessity” …’ and went on to add, ‘It is the same necessity that in language marlts out the grammatical meanings.’ In his ‘Yeats’ “Sorrow of Love” through the Years’ written along with Stephen Rudy they drew attention to Yeats’s predilection for “art that is not mere story – telling”. They went on:

According to Yeats, “the arts have already become full of pattern and rhythm. Subject pictures no longer interest us.” In this context he refers precisely to Degas, in Yeats’ opinion an artist whose excessive and obstinate desire to ‘picture’ life – “and life at its most vivid and vigorous” – had harmed his work.

Jaltobson and Rudy go further and point out,

The poet’s emphasis on pattern reminds one of Benjamin Lee Whorf, the penetrating lingiust who realized that ‘the patternment’ aspect of language always overrides and controls the ‘lexation’ or name-giving aspect,” and an inquiry into the role of “pattern” in Yeats’ own poetry becomes particularly attractive, especially when one is confronted with his constant and careful modification of his own works.
The two authors go on and draw attention to Yeats’ epigraph to his Collected Work  Verse And Prase which reads.