Most cultured people of the higher races of the world have this development to some extent: that is to say, the senses of their astral bodies are in full working order, and perfectly capable of receiving impressions from objects and entities of their own plane. But to make that fact of any use to them down here in the physical body, two changes are usually necessary; first, that the Ego shall be awakened to the realities of the astral plane, and induced to emerge from the chrysalis formed by his own waking thoughts, and look round him to observe and to learn; and secondly, that the consciousness shall be so far retained during the return of the Ego into his physical body as to enable him to impress upon his physical brain the recollection of what he has seen or learnt. If the first of these changes has taken place, the second is of little importance, since the Ego, the true man, will be able to profit by the information to be obtained upon that plane, even though he may not have the satisfaction of bringing through any remembrance of it into his waking life down here. Students often ask how this clairvoyant faculty will first be manifested in themselves--how they may know when they have reached the stage at which its first faint foreshadowings are beginning to be visible. Cases differ so widely that it is impossible to give to this question any answer that will be universally applicable. Some people begin by a plunge, as it were, and under some unusual stimulus become able just for once to see some striking vision; and very often in such a case, because the experience does not repeat itself, the seer comes in time to believe that on that occasion he must have been the victim of hallucination. Others begin by becoming intermittently conscious of the brilliant colours and vibrations of the human aura; yet others find themselves with increasing frequency seeing and hearing something to which those around them are blind and deaf; others, again, see faces, landscapes, or coloured clouds floating before their eyes in the dark before they sink to rest; while perhaps the commonest experience of all is that of those who begin to recollect with greater and greater clearness what they have seen and heard on the other planes during sleep. Having now to some extent cleared our ground, we may proceed to consider the various phenomena of clairvoyance.