accompaniment. While it is often associated with music of the Romantic Period, classical performers frequently use rubato for emotional expressiveness in all kinds of works. The opinion given by Tom S. Wotton, that "every bar has its proper time value" may be regarded as an inaccurate description: Karl Wilson Gehrkens mentions "duration taken from one measure [...] and given to another" which implies bars of differing duration. Rubato relates to phrasing; and since phrases often go over multiple bars; it is often impossible (and also not desired) for each bar to be identically long. Early twentieth century Early twentieth-century rubato seems to be very eventful. Robert Philip in his book Early recordings and musical style: Changing tastes in instrumental performance, 1900-1950 specifies three types of rubato used at that time: accelerando and rallentando, tenuto and agogic accents, and melodic rubato. Accelerando and rallentando Late 19th century dictionaries of musical terms defined tempo rubato as "robbed or stolen time." This effect can be achieved by a slight quickening of speed in ascending passages, for instance, and calando on descending phrases. Ignacy Jan Paderewski says that tempo rubato relies on "more or less important slackening or quickening of the time or rate of the movement." Many theoreticians and performers claimed at that time that the "robbed" time must be eventually "paid back" later within the same measure, so that the change of tempo would not affect the length of the measure. However, the balance theory caused controversy, as many theoreticians dismissed the assumption that the "stolen" time should necessarily be "paid back." In the third edition of Grove's Dictionary we read: "The rule has been given and repeated indiscriminately that the "robbed" time must be "paid back" within the bar. That is absurd, because the bar line is a notational, not a musical, matter. But there is no necessity to pay back even within the phrase: it is the metaphor that is wrong." Paderewski also discarded this theory saying: "(...) the value of notes diminished in one period through an accelerando, cannot always be restored in another through a ritardando. What is lost is lost." Some theoreticians, however, rejected even the idea that rubato relies on accelerando and ritardando. They were not recommending that a performance should be strictly metronomic, but they came up with a theory saying that rubato should consist of tenuto and shortened notes. Tenuto and agogic accents The