Rubato is a rhythmic structural model that goes back to John Cage's Lectures on Nothing and can be understood as an extension or shortening of the text in the performance, usually combined with the demand that the "stolen time" must be returned. The pattern goes back to an asyntactic sequence of sentences, phrases, words, syllables and letters that Cage developed by chance according to the Chinese Book of Changes, the I Ching. The I Ching is an oracle book that provides a description of the world in 64 hexagrams and was used in its column form as a model for Cages Lectures on Nothing and Lectures on Something. These 64 different hexagrams consist of six lines, each of which can be of two different types: As a solid horizontal line (hard) and as a horizontal line interrupted in the middle (soft). The Lecture on Nothing, written by Cage in 1949, follows this structure given by the I Ching as a spoken score. This in turn explains the course of rubato resulting from the random principle of the I Ching, as Cage explains in his introduction:
‘There are four measures in each line and twelve lines in each unit of the rhythmic structure. There are forty-eight such units, each having forty-eight measures. The whole is divided into five large parts, in the proportion 7, 6, 14, 14, 7. The forty-eight measures of each unit are likewise so divided. The text is printed in four columns to facilitate a rhythmic reading. Each line is to be read across the page from left to right […]. This should not be done in an artificial manner (which might result from an attempt to be too strictly faithful to the position of the words on the page), but with the rubato which one uses in everyday speech. (Cage 1961: 109).
The use of the I Ching as a random generator of the composition leads to a rhythmization principle resulting from the comparable column arrangement of Lectures on Nothing. The reading voice partly rushes ahead, partly it can be left behind. Because the parallel percussion, however, remains strictly in time, speaking voice and percussive accompaniment are desynchronized in an unpredictable way.
Ernst Jandl used this principle in his stereo radio play with Friederike Mayröcker entitled "Der Uhrensklave" (The Watch Slave) from November 1969, after translating John Cage's "Silence" in the same year. According to Jandl, "Der Uhrensklave" is also "an experiment with time". Jandl distinguishes between "current", "subjective" and "fictitious (standardized, objective')" time: three forms that are parallelized by a comparable arrangement of columns in the text image and in the performance. Thus, displacements of three tenses comparable to the rubato rhythm of cage arise: Some hurry ahead, some stay behind.
An example of this rhythm within poetry is the work of Bodo Hell, who collaborated with Friederike Mayröcker and Ernst Jandl, among others: a rubato can be found in the poem brav bergwärts: