The motivation derives from a sense that the entities that organize time - - in particular the beat and the hierarchy of beats , are of a significantly different kind from the elements at work in part 1 - - gestural elements of melody such as figures and phrases 這動機是從對組織時間本體的一個感覺而來的?尤其是拍和拍的等級,是和第一部份課堂中的元素有特別的不同?旋律所表現(xiàn)出來的元素例如音形和樂句。