Chant (from Old French “chanter”) is the rhythmic speaking or the singing of words or sounds, often primarily on one or two pitches called reciting tones. Chants may range from a simple melody involving a limited set of notes to highly complex musical structures, often including a great deal of repetition of musical sub phrases. Chant may be considered speech, music, or a heightened or stylized form of speech. In the later Middle Ages, some religious chant evolved into song (forming one of the roots of later Western music).
So, what is the essence of chant that so many rituals, rites, and rewards promise? I am not a scholar in this regard, so I will simply speak from my own experience and observations.