The variable foot was developed by William Carlos Williams in his work "Patterson" and is based on the idea that each line corresponds exactly to one single breath unit. Unlike cadence, the length of the line corresponds to a colon, so it is an isocolic rhythmical pattern. This is based on William Carlos Williams' idea of "the variable foot" and its triadic "step-down-line" developed in the 1940s in his volumes The Desert Music and Journey to Love as well as in Paterson V.
Williams understood his theory of the "variable foot" and the related "step-down-line" as the "solution to the problem of the modern verse", the "culmination" of a lifelong search for a new form of prosody (cf. Cushman 1985). Williams' triadic arrangement of the somewhat more indented three-liners follows a rhythmic or post-metric principle, because despite the sometimes highly divergent accumulation of syllables in the individual lines, the rhythm of each individual line is isochronic. Each individual line spans a single stress arc, the time interval between two lines is always approximately the same. The following excerpt from the poem Asphodel, that Greeny Flower shows this. It is oriented to the American everyday language; the graphic arrangement of the individual lines corresponds to the division of the text into even rhythmic units:
I have learned much in my life
and out of them
is not the end of it.
There is a hierarchy
which can be attained,
in its service.
is a fairy flower;
a cat of twenty lives.
If no one came to try it
would be the loser.
As the inventor of the variable Versfuß and its step down line, Williams became the model for the Black Mountain poets Charles Olson, Robert Duncan, Robert Creeley and Denise Levertov as well as the authors of the beat generation - Allen Ginsberg, Lawrence Ferlinghetti, Jack Kerouac and William S. Burroughs - as John Lowney could show. In Germany, his poems were translated and published around 1951 in the journal Fragmente, published by the young Rainer Maria Gerhardt, followed later by Walter Höllerer in the journal Akzente and Hans Magnus Enzensberger in the Museum of Modern Poetry in 1960, where Williams is the most important American author after Ezra Pound. In addition to Enzensberger, authors such as Nicolas Born, Jürgen Becker and Rolf Dieter Brinkmann are influenced by Williams' variable foot, its line arrangement and its variable foot. The most important example of the variable foot and its idea of the 'breath controlled line', however, has been developed by Ernst Jandl.
Berry, Eleanor: 'Williams' Development of a New Prosodic Form-Not the 'Variable Foot,' But the Sight Stanza, in: William Carlos Williams Review 7 (1981), S. 21-29.
Cushman, Stephen : William Carlos Williams and the Meanings of Measure, New Haven and London: Yale University Press 1985.
Lamping, Dieter: William Carlos Williams, deutsch: Zur Rezeption moderner amerikanischer Lyrik in Deutschland, in: Arcadia: Internationale Zeitschrift für Literaturwissenschaft, 1994, Vol.29(1), S. 43-57.
Lowney, John: The American Avant-Garde Tradition: William Carlos Williams, Postmodern Poetry, and the Politics of Cultural Memory, Bucknell University Press 1997.
Williams, William Carlos: Pictures from Brueghel and Other Poems: Collected Poems 1950-1962, New York 1962, S. 157.