William Walker Atkinson 
Practical clairvoyance, psychomancy and crystal gazing 

The term ‘Psychomancy’ (pronounced, ‘sy-ko-man-see’), is derived from two Greek words, the first ‘psycho, ‘ meaning ‘the soul; the mind; the understanding’ (and generally used to indicate ‘psychic’ or unusual powers of the soul or mind); the second word, ‘mancy’ meaning ‘to divine; to foresee, or foreknow; to detect secret things, ‘-and in occult parlance, ‘to sense, ‘ or ‘to receive impressions by the Astral Senses.’ So the word, as we use it, may be said to mean ‘Psychic Sensing, ‘ and in this work will be so used. The word ‘Psychomancer’ means ‘one practicing Psychomancy;’ and the word ‘Psychomantic’ means ‘relating to Psychomancy.’
The word ‘Clairvoyance’ is frequently used by people to designate some of the phases of Psychomancy, but strictly speaking this term is incorrect when used in this sense, the true occult meaning of the word ‘Clairvoyance, ‘ being ‘transcendental vision, or the perception of beings on another plane of existence?the seeing of disembodied souls, elementals, etc.’ And so, in this work, we shall consider the true phenomena of Clairvoyance, as distinct from that of Psychomancy.