Meister Eckhart, a 13th century Christian mystic living in Germany, describes the practice of "gelassenheit," or non-attachment. Most contemplative traditions have a version of this concept and cultivate holding life and ideas with an open palm. This is a Buddhist precept as well. In yoga philosophy, aparigraha means non-grasping. We let go of how we would have life be, and welcome in the way things actually are, which includes acknowledging how little we know. Just like John of the Cross, Eckhart described God as "no-thing," meaning that God is not an object we can possess, but a reality that is far greater than our human comprehension.
We let go of who we are certain of God to be and cultivate an openness to the One who is far beyond the horizons of our imagining. In the Book of Job, God challenges Job's desire for understanding and asks "where were you when I laid the foundation of the earth?" God is never a set of concepts to be understood and grasped, but a relationship to encounter and engage. In this way, the spiritual life is always a journey and in process. We do not let go once and for all, but move through the layers of clinging in our lives until we are living more from our hearts than our minds. We do not arrive, but travel toward the horizon, realizing that it is always receding from our view.