If we wish to retain thought, or transmit thought, we must learn the process of "throwing the ball" to hit a certain goal. 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, and the aiming, whereby one focuses one's mental eye upon the other in telepathy, is concentration. In brief, two things are necessary for telepathy: strength of will and power of concentration.