210.42 Hz is Cousto's octave of the synodic month, the cycle from new moon to new moon raised into sound. The Moon is the tradition's image of tide, feeling, and rhythm. It reads as a tone of ebb and flow, used for settling and for cyclical, restful practice. In The Cosmic Octave (1978) Hans Cousto set out a simple, exact method: take the period of an astronomical cycle (an orbit, a rotation, a synodic month) and double its frequency, octave upon octave, until it rises into audible sound. The result is a tuning fork for each body in the solar system. This system is the complete table, from the fast tone of Mercury to the slow swing of Pluto. Independent of any tradition, controlled clinical evidence that a specific frequency produces a specific health effect is limited and mixed. Auriviel presents these tunings as music and contemplative practice. This page is for general information and relaxation. Auriviel's frequency music is not medical advice, diagnosis, or treatment, and no health outcome is claimed. If you have a medical concern, please consult a qualified professional.