What is the X in X-mas?
singing of psalms in worship. In biblical times professional singers chanted psalms during Jewish religious services. Occasionally, the congregation interpolated a short refrain between the chanted verses. The alternation of soloist and chorus was called responsorial psalmody (see responsory). Another method, antiphonal psalmody, was the alternation by two half choirs in the singing of psalm lines or half lines (see antiphon). Psalms were also sung without either refrain or alternating singers (direct psalmody). These methods of psalmody were adopted by the early Christian Church in the East and West. Early Christian psalmody was the germ from which evolved both the classical Gregorian chant and also the Byzantine, Ambrosian, and other Christian chants (see also psalm tone).