The Inner Experience: Notes on Contemplation.

[T]he inner self is not a part of our being, like a motor in a car. It is our entire substantial reality itself, on its highest and most personal and most existential level. It is like life, and it is life: it our spiritual life when it is most alive. It is the life by which everything else in us lives and moves. It is in and through and beyond everything that we are. If it is awakened, it communicates a new life to the intelligence in which it lives, so that it become a living awareness of itself: and this awareness is not so much something that we ourselves have, as something that we are. It is a new and indefinable quality of our living being.

Source: Thomas Merton. The Inner Experience: Notes on Contemplation. William H. Shannon, editor (San Francisco: HarperSanFrancisco, 2003): 6.