absolutely necessary indeed, but still not telling you how to
reach the conditions put before you. The special literature of
Yoga is, first of all, many of the minor Upanishads, "the
hundred-and-eight" as they are called. Then comes the enormous
mass of literature called the Tantras. These books have an evil
significance in the ordinary English ear, but not quite rightly.
The Tantras are very useful books, very valuable and instructive;
all occult science is to be found in them. But they are divisible
into three classes: those that deal with white magic, those that
deal with black magic, and those that deal with what we may call
grey magic, a mixture of the two. Now magic is the word which
covers the methods of deliberately bringing about super-normal
physical states by the action of the will.

A high tension of the nerves, brought on by anxiety or disease,
leads to ordinary hysteria, emotional and foolish. A similarly
high tension, brought about by the will, renders a man sensitive
to super-physical vibrations Going to sleep has no significance,
but going into Samadhi is a priceless power. The process is
largely the same, but one is due to ordinary conditions, the
other to the action of the trained will. The Yogi is the man who
has learned the power of the will, and knows how to use it to
bring about foreseen and foredetermined results. This knowledge
has ever been called magic; it is the name of the Great Science
of the past, the one Science, to which only the word " great "
was given in the past. The Tantras contain the whole of that; the
occult side of man and nature, the means whereby discoveries may
be made, the principles whereby the man may re-create himself,
all these are in the Tantras. The difficulty is that without a
teacher they are very dangerous, and again and again a man trying