This book offers a philosophical account of ordinary consciousness as a step toward understanding mystical consciousness. Presupposing a living interaction between meditation and thinking, the work draws on Western and Japanese thinkers to develop a philosophy of religion that is friendly to the experience of meditators and that can explore such themes as emptiness, nothingness, and the self. Western thinkers considered include Plotinus, Eckhart, Schleiermacher, Heidegger, Brentano, Husserl, Sartre, and Lonergan; and Japanese thinkers referenced include Nishitani, Hisamatsu, and Suzuki. All employed centering prayer, Zen, or other forms of mental concentration. Particular emphasis is placed on the work of twentieth-century Catholic philosopher Bernard Lonergan, whose writings on consciousness can inform an understanding of mysticism.