The training in concentration is practice to make the mind firm and steady. This brings about peacefulness of mind. Usually our untrained minds are moving and restless, hard to control and manage. Mind follows sense distractions wildly just like water flowing this way and that, seeking the lowest level. Agriculturists and engineers, though, know how to control water so that it is of greater use to mankind. Men are clever, they know how to dam water, make large reservoirs and canals — all of this merely to channel water and make it more useable. In addition the water stored becomes a source of electrical power and light, further benefits from controlling its flow so that it doesn’t run wild and eventually settle into a few low spots, its usefulness wasted.
So too, the mind which is dammed and controlled, trained constantly, will be of immeasurable benefit. The Buddha Himself taught, “The mind that has been controlled brings true happiness, so train you minds well for the highest of benefits.” Similarly, the animals we see around us — elephants, horses, cattle, buffalo, etc., must be trained before they can be useful for work. Only after they have been trained is their strength of benefit to us. ~Ajahn Chah