The difference between clairvoyance and clairaudience is that clairvoyance manifests in the form of a vision that one can see with the inner eye. Clairaudience manifests as a voice, as a word that one can hear with the inner ear. The mediumistic knowledge therefore differs from it. Mediumistic knowledge comes either by a continual obsession or by a momentary obsession, by a voluntary obsession or by an involuntary obsession.