This impediment comes from the contribution made by the nervous system to the auditory process. In order to understand the nature of this contribution we must remember the role played by the blood in seeing. It was found by us to consist in the bringing about of that state of equilibrium without which we should experience light merely as a pain-producing agent. Similarly, the perception of sound requires the presence of a certain state of equilibrium between the nerve-system and the limb-system. In this case, however, a lack of equilibrium would result not in pain, but in ecstasy. For if acoustic impressions played directly into our limb-system, with nothing to hold them in check, every tone we encounter would compel us to an outward manifestation of astral activity. We should become part of the tone-process itself, forced to transform it by the volitional part of our astral organization into spatial movement. That this does not happen is because the participation of the nervous system serves to damp down the potential ecstasy. Hence it is more or less left to the sentient part of the astral organization - that is, the part free from the physical body - to partake in the astral processes underlying the tone occurrences.