When this thought-form reaches its object it discharges itself into his astral and mental bodies, communicating to them its own rate of vibration. Putting this in another way, a thought of love sent from one person to another involves the actual transference of a certain amount both of force and of matter from the sender to the recipient, and its effect upon the recipient is to arouse the feeling of affection in him, and slightly but permanently to increase his power of loving. But such a thought also strengthens the power of affection in the thinker, and therefore it does good simultaneously to both. Every thought builds a form; if the thought be directed to another person it travels to him; if it be distinctly selfish it remains in the immediate neighbourhood of the thinker; if it belongs to neither of these categories it floats for awhile in space and then slowly disintegrates. Every man therefore is leaving behind him wherever he goes a trail of thought forms; as we go along the street we are walking all the time amidst a sea of other men's thoughts. If a man leaves his mind blank for a time, these residual thoughts of others drift through it, making in most cases but little impression upon him. Sometimes one arrives which attracts his attention, so that his mind seizes upon it and makes it its own, strengthens it by the addition of its force, and then casts it out again to affect somebody else. A man 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.