Leaves of Morya's Garden - Book 2 - Illumination (1925) - 2.9.5: During the best periods of priesthood's reign the chosen words were: "Adonai," "Ishtar," "Alleluia," and "Aum." Also, the repetition of the alphabet or of figures was in use. Of course, actually the power is not in the words themselves but in the creation of waves.