The reason that so many recorded cases have occurred when the clairvoyant person was asleep, and the vision appeared as a dream, is simply because in such a condition the physical senses of the person are stilled and at rest, and there is less likelihood of interference from them, and a better opportunity for the astral senses to function effectively. It is like the familiar cases in which one becomes so wrapped up in viewing a beautiful work of art, or in listening to a beautiful musical rendition, that he or she forgets all about the sights and sounds of the world outside. One sometimes gets into this same condition when reading an interesting book, or when witnessing an interesting play. When the psychic powers are concentrated upon any one channel of vision, the others fail to register a clear impression. The same rule holds good on the astral plane, as on the physical. There are certain psychic conditions which are especially conducive to the manifestation of clairvoyant phenomena, as all students of the subject know very well. These conditions are somewhat hard to induce, at least until the clairvoyant has had considerable experience and practice. But, in the state of sleep, the person induces the desired conditions, in many cases, though he is not consciously doing so. As might naturally be expected, therefore, the majority of the recorded cases of clairvoyance have occurred when the clairvoyant person has been asleep. I should also state, once more, that in many cases in which the clairvoyant has witnessed the "appearance" of another person, as in the cases such as I have just mentioned, there is always the possibility of the person having actually appeared in his astral body, unconsciously to himself of course. No one but a skilled occultist is able to distinguish between cases of this kind. The line between this class of clairvoyance and astral appearance is very thin, and, in fact, the two classes of phenomena shade and blend into each other. In reality, when one gets down to bottom principles, there is very little difference between the actual appearance in the astral body, and the strong projection of one's presence by means of will, conscious or unconscious, along the lines of awakening the clairvoyant vision of others. To attempt to explain the slight points of difference here, would only involve the student in a mass of technical description which would tend to confuse, rather than to enlighten him--from this I refrain. LESSON XI. CLAIRVOYANCE OF THE PAST The third great class of clairvoyant phenomena, known as Time Clairvoyance, is divided into two sub-classes, as follows: (1) Past-Time Clairvoyance; and (2) Future-Time Clairvoyance. The characteristics of each of these sub-classes is indicated by its name.