Remember David and his Psalmody?
Five main streams of inherited material flow together into the chant, and within the melodic classifications of the chant they remain formally distinguishable from each other to this day. These include Jewish solo psalmody, whose basic model is preserved in the Invitatory, the Responsories, and the Tract; the monastic choir psalmody of the Divine Office; the ancient art of depicting faith in song; the ancient cantillation of the priests and lectors in the tones of orations and readings; and the popular elements of various kinds in the acclamations, doxologies, and simple hymns and antiphons.
The chant unites elements from ancient Jewish, monastic, priestly, and popular practices in various types of chants.