The history of music must necessarily be the history of musical performance. The earliest effort at making any musical sound must have been that of the voice, and the progress of music through its various stages is the evolution of sound from singing in single voices or unison or octaves, passing through the organum and diatessaron stages to the polyphony of the modal period, illustrating the progress from individual to combined vocal music-making: this represents the actual music-making by the purely human element. Inevitably, with the use of rhythm, possibly beginning with a form of dancing to the accompaniment of some percussion instrument, mechanical instruments, by which I mean instruments needing physical skill to play them, were evolved from the primitive psalteries and sackbuts to the modern instruments of the orchestra. In all music-making there was a need for a unifying instrument, something which one person could manipulate which would bind together a body of musicians and be as it were a means of reference in the matter of pitch and rhythm. We have little information concerning the great music-makings of old of which we read in the Old Testament—the great song of Deborah and Barak and the thanksgiving songs of David and his followers, for instance—and we do not know whether they had conductors or not; but we do know that they had psalteries and sackbuts and cymbals.