Chopin was the first to set this style in his compositions, which gave his performance of musical pieces his characteristic signature: with this we mean Tempo Rubato. A fading, irregularly interrupted tempo, supple, fragmentary and languishing at the same time, flickering like the flame in the moving breeze of air. Later he didn’t use to add the term for this tempo when publishing his work, convinced that, whoever had the understanding in the first place, would automatically discover the law of this independence… All of Chopin’s pieces must be played with that way of accentuated and prosodic, swaying mobility, whose secret one can hardly unravel if you haven’t had the chance to hear him frequently… He seemed eager to teach his students this style, but preferably his fellow-countrymen, he wanted them to interpret in his way more than others.
Rhythm is never the keeping of time in a low, common sense of symmetry as monotony. Rhythm is the proportional structure in an infinite sense of spiral vibrations and individualising asymmetry, where the moving closer of ratios comes and passes.
Rhythm in a superior sense is never to be exchanged with the completed development of circles. It starts in the good or first part of the beat and proves that it also has this infinite spiral characteristic, by subjecting the bad or second part of the beat to itself. The second part is shorter than the first.
In the same way, the second and third tone in a triplet are shorter than the introducing tone. Thus, the tones in a motive are not the same machine stitches, but rather not identically arranged from a rhythmical point of view.
This harmonious development never lets two beats next to each other be exactly the same in time, and no phrase can be rhythmical, without this individualising spirit of dissimilarity moderating the beats.”

“When Liszt played the most difficult places of bravura, and the longest cadenzas, which sooner or later seemed to me to be superfluous virtuoso frippery when any other virtuosi performed it, he gave the impression as if generously scattering blossoms and pearls.”

F.H. Clark
Conversations with Liszt

“Then Liszt played me a scale, and I noticed that the motifs were grouped in phrases. Each motif was in itself clear, and agogically as well as dynamically shaded throughout. The tones did not just sound regular, not the same, but were in the shape of a curve, and were to any tone in different moderating ratios. I also heard that the motifs in the series were unequal. That gave the series of motifs as well as the motifs modulation in itself. I told Liszt that this was a complex rhythm like with the ocean waves, where the smaller ones roll out from the larger ones, and the larger ones have a clear swinging shape.

Then Liszt played Chopin’s Waltz in flat major.

I’ll never forget how the time motif, vividly designed, with regard to agogics and dynamics differently shaded, were in the phrase, so that the phrase developed a shape in itself, which received the mark of perfection through the fact that the links were unequal. When counting the same beats, that would have been impossible, as every individualising requires unequal structuring.

I said:” Truly, this vividness is like the fleeting smoke of incense or like the aspen, which sways in the summer wind at the source in the lover’s grove; so certain and yet so different are all parts, which I perceive in this complex grouping.”

“It is obvious”, Liszt said, “that you now notice the evolution in my tempo, the harmonious development of the rhythm; as this is only a reflection of my technique. As you said about the ocean just now, that the little waves push into the waves, the waves into the currents, likewise I have rhythms in my upper arm, which the lower arm rhythms understand in themselves, the latter move the hand rhythms through their own swing into a flooding movement.

But none of these harmonious developments of rhythm could happen if you made the beat into a unity of tempo or if you thought of equal counting times or applied them when playing.

The harmonious development of rhythm or tempo is stopped and destroyed just at that moment, when two consecutive counting times are the same.
To count two neighbouring beats the same, is a violation against aesthetics - indeed the worst kind.

Particularly in relation to the metronomising of beats and counting times, which musicians usually call classical, rhythmical, Schiller says: “Music still stands in greater affinity to the senses than true aesthetic freedom allows it to.”

Indeed, here in the inexorable dissimilarity of rhythms in themselves and among each other, is the divine infinity of my art.
That is what I wrote as an apotheoses at the end of my twelfth symphonic poetic work, that this “inexorable application of the ideal” is the highest purpose in our life.

The divinity of this application is based on its all-round, continuing, indeed infinite designing, shaping, moderating of opposites in every conceivable direction. We have this exactly and absolutely in the periodic presentation of the forms of rhythms.”

Then Liszt played me his “Forest Murmurs“, saying: “Now I will show you how a source really bubbles.”

It appeared to me as the absolute embodiment of gracefulness in the performance of art. I never saw him breaking or hitting, falling or throwing, swinging or swaying, but there were spontaneous, extensive, treble impulses continuously bubbling out - indeed a mixtum compositum in an energetic outbreak - which modulated themselves through these complex wave shapes and in many ways intertwining lines, - a real stream of life.”
“So what is the actual purpose of finger exercises?”I asked.

“Any possible finger exercise during piano studies has no other purpose”, Liszt answered, “than to demoralise the human will, and rob him of all his senses of the divine, to foil any human striving for harmony and the musical in any activities.

This has been invented by the wrong instinct, in order to oppose the aesthetic spirit of the unifying, the structuring, and to place a barrier in front of any longing for true, musical virtuosity. All these finger skills are merely devised by people, who only interfere without knowledge, without having understood the gist of freedom.”

Then Liszt played me his ‘Will o’the Wisp’, and it became increasingly clear to me that harmony must develop from contrasts, and could never exist in simple symmetry. Use of the same beat is only monotony, and opposes any development towards shaping freedom.”