There is a sign outside a casino in Las Vegas that says, "You must be present to win." The same is true in meditation. If we want to see the nature of our lives, we must actually be present, aware, awake. Developing samadhi [concentration] is much like polishing a lens. If we are looking to see the cells and workings of the body with a lens that has not been ground sufficiently, we will not see clearly. In order to penetrate the nature of the mind and body, we must collect and concentrate our resources and observe with a steady, silent mind. This is exactly what the Buddha did: he sat, concentrated his mind, and looked within. To become a yogi, an explorer of the heart and mind, we must develop this capacity as well.
~ Jack Kornfield, Seeking the Heart of Wisdom