Curt Sachs may have put his finger on what is at issue here in 'Rhythm and Tempo' in 1953, when he discovered that "rhythm" itself … is a primeval word with antithetical senses. On the one hand "rhuthmos" (Greek) denoted river or flow. On the other, "rhythmus" (Latin) denoted blockage or dam. Sach's point is not that Greeks and Romans had different cultural coordinates … but that coiled within rhythm itself was a certain undecidability – perhaps the very same undecidability that Derrida traces in the connotative oscillations of "tympan".