The mind is prone to gathering experiences and storing them in the memory. It does not know the art of giving up. Nothing is cast away by the mind. As a consequence, grief, anxiety, and misery continue simmering in it. If only the mind can be taught tyaga (sacrifice), one can become a Yogi (spiritually serene person). The clock, to all appearances, keeps on ticking away continuously. But this is really not the case. It is not continuous, for there is, one can notice, a short pause between one tick and the next. That is the interval of rest. But the mind does not have even this short interval between one thought and the next. And in the continuous succession of thoughts, there is no order or relationship. This adds to the confusion and concern. This is the main source of ill-health in man. We are at present planning and preparing for physical rest and recreation, and we know that even machines need hours of rest! But we have neglected the duty of ensuring rest for the mind. Dhyana (meditation) is the name for the period of rest we provide for the busy and wayward mind.