therefore, is not responsible for a thought which floats into his
mind, because it may be not his, but someone else's; but he _is_
responsible if he takes it up, dwells upon it and then sends it out
strengthened.

Self-centred thought of any kind hangs about the thinker, and most men
surround their mental bodies with a shell of such thoughts. Such a shell
obscures the mental vision and facilitates the formation of prejudice.

Each thought-form is a temporary entity. It resembles a charged battery,
awaiting an opportunity to discharge itself. Its tendency is always to
reproduce its own rate of vibration in the mental body upon which it
fastens itself, and so to arouse in it a like thought. If the person at
whom it is aimed happens to be busy or already engaged in some definite
train of thought, the particles of his mental body are already swinging at
a certain determinate rate, and cannot for the moment be affected from
without. In that case the thought-form bides its time, hanging about its
object until he is sufficiently at rest to permit its entrance; then it
discharges itself upon him, and in the act ceases to exist.

The self-centred thought behaves in exactly the same way with regard to its
generator, and discharges itself upon him when opportunity offers. If it be
an evil thought, he generally regards it as the suggestion of a tempting
demon, whereas in truth he tempts himself. Usually each definite thought
creates a new thought-form; but if a thought-form of the same nature is
already hovering round the thinker, under certain circumstances a new
thought on the same subject, instead of creating a new form, coalesces with
and strengthens, the old one, so that by long brooding over the same
subject a man may sometimes create a thought-form of tremendous power. If
the thought be a wicked one, such a thought-form may become a veritable
evil influence, lasting perhaps for many years, and having for a time all
the appearance and powers of a real living entity.

All these which have been described are the ordinary unpremeditated
thoughts of man. A man can make a thought-form intentionally, and aim it at
another with the object of helping him. This is one of the lines of
activity adopted by those who desire to serve humanity. A steady stream of
powerful thought directed intelligently upon another person may be of the
greatest assistance to him. A strong thought-form may be a real guardian
angel, and protect its object f