Sound rises within when the higher centers awaken, heard as an inner voice rather than an outer one. The many waters are the massed emotional and life-currents of a person moving in unison, and the great thunder is the deep vibration felt in the body when spiritual force gathers to a peak. The harpers are the awakened nerve-centers played like strings, each vibrating at its own pitch, and their music is the tuned harmony of a being brought into accord.
What happens inside is that the awakened person begins to perceive an inner sound, the felt resonance of the body's energies flowing together. The scattered forces that once made noise now play as one instrument, and the harmony of the whole self becomes audible from within.
Many waters: the massed emotional and life-currents of a person moving as one
Great thunder: the deep vibration felt in the body when spiritual force gathers to its peak
Harpers and harps: the awakened nerve-centers played like strings, sounding the tuned harmony of the whole being