I should not advise anyone to allow himself to be thrown into mesmeric sleep for the purpose of gaining clairvoyant experiences. The domination of the will by that of another produces effects that few people realize. The will of the victim becomes weaker, and is more liable to be acted upon by others. In the scheme of things no man is forced to do anything; he is taught by receiving always the result of his actions; and it is better to allow clairvoyant powers to come gradually in the normal course of evolution, rather than to try to force them in any way.
We must not always assume that a man who sees something pertaining to higher planes is necessarily becoming clairvoyant. By clairvoyance, for example, we may undoubtedly see an apparition, but on the other hand there are various other ways in which a man may see or suppose himself to see something which to him would be exactly the same as an apparition.
The apparition of a dead person may be as follows:
(a) one's own imagination,
(b) A thought form produced by another person,
(c) or by the person seen,
(d) an impersonation,
(e) the etheric double of the person, or
(f) the real person actually there. In the last case one of three things must have happened--that is, supposing that the apparition is dead or sleeping and in his astral body, and that the man who sees him is himself in the physical body and wide awake.
(a) the dead man has materialized himself, and is for the time a physical object, which may be seen by any number of people with ordinary physical sense;
(b) the dead man is in his astral body, in which case only those possessing astral sight can perceive him; he has probably succeeded by some special effort in temporarily opening that sight for the person to whom he wishes to show himself, and is therefore most likely visible to that one person only, and not to any others who may happen to be present; or,
(c) the dead man has mesmerized the living, so as to impose upon him the idea that he sees a figure which is not really visible to him, though it may be really present.
If the apparition be an etheric double, it will not stray far away from the dense body to which it belongs or used to belong. An unpracticed apparition--one who is it new to the astral plane--often shows traces of the habits of his earth-life. He will enter and depart by a door or window, not yet realizing that he can pass through the wall just as easily. I have even seen one squeeze through the crack of a locked door; he might as well have tried the keyhole! But he moves as he has been accustomed to move--as he thinks of himself as moving. For the same reason an apparition often walks upon the earth, when he might just as well float through the air.
It is a mistake to think that if you see a vision, it must necessarily mean something for you, or be specially sent to you. If you for the moment become sensitive, you see what ever happens to be there: Suppose I am sitting in a room, and the curtain is drawn across the window, so that the street outside is invisible to me. Suppose the wind lifts the curtain for a moment, so that I get a glimpse of the street, I shall then see what ever happens to be passing at that moment. Let us imagine that I see a little girl in a red cloak, carrying a basket. The little girl is probably going about her own business, or perhaps her mother's; should I not be foolish if I chose to fancy that she had been sent there especially for me to see, and began to worry myself as to what could be symbolized by the red cloak and a basket? A flash of clairvoyance is usually just the accidental lifting of a curtain, and generally what is seen has no special relation to this seer.
There may occasionally be instances in which the curtain is in intentionally lifted by a friend because something of personal interest is passing; but we must not be too ready to assume that that is the case.