These then are the conditions: a current must be established, a channel or opening along which or through which the sound or words can reach another person. Secondly, the sound must not be able to scatter in all directions, but must be directed and concentrated towards the other so that it can reach the inner or mental sound which we call thought. If we wish to retain thought, and transmit thought, we must learn the process of throwing "the ball" to hit a certain aim. We must direct our aim right, and we must put enough force in it to enable it to reach the goal. It is the force of the will that sends the thought to reach another person. The aim whereby the first person focuses his mental eye upon the other, in telepathy, is concentration. In brief, two things are necessary for telepathy - strength of will, and power of concentration.