Jesus uses yeast in both a positive way, to describe a growth-inducing “yeast which is hidden inside the dough” (see Matthew 13:33), and in a very negative way, when he warns the disciples against “the yeast of the Pharisees and of Herod” (see Mark 8:15).
I would like to suggest these passages tell us that leaven or yeast is a metaphor for things hidden in the unconscious, which will have a lasting effect on us if we do not bring them to consciousness. Carl Jung seemed to think that ninety percent of our energy—good and bad—resides in the unconscious, over which we have little direct control or accountability.
If we do not discover a prayer practice that “invades” our unconscious and reveals what is hidden, we will actually change very little over our lifetime. This was much of the genius of John of the Cross (1542–1591) who, in a highly externalized Spanish Catholicism, spoke from personal experience of darkness, inner journeys, and the shadow self. He was centuries ahead of the modern discovery of the unconscious, and thus many of his fellow Carmelites considered him heretical and dangerous.
Prayer should not be too rational, social, verbal, linear, or transactional. It must be more mysterious, inner, dialogical, receptive, and pervasive. Silence, symbol, poetry, music, movement, and sacrament are much more helpful than mere words.
When you meditate consistently, a sense of your autonomy and private self-importance—what you think of as your “self”—falls away, little by little, as unnecessary, unimportant, and even unhelpful. The imperial “I,” the self that you likely think of as your only self, reveals itself as largely a creation of your mind.
Through regular access to contemplation, you become less and less interested in protecting this self-created, relative identity. You don’t have to attack it; it calmly falls away of its own accord and you experience a kind of natural humility.
If your prayer goes deep, “invading” your unconscious, as it were, your whole view of the world will change from fear to connection, because you don’t live inside your fragile and encapsulated self anymore.
In meditation, you move from ego consciousness to soul awareness, from being fear-driven to being love-drawn. That’s it in a few words!
Of course, you can only do this if Someone Else is holding you, taking away your fear, doing the knowing, and satisfying your desire for a Great Lover. If you can allow that Someone Else to have their way with you, you will live with a new vitality, a natural gracefulness, and inside of a Flow that you did not create. It is actually the Life of the Trinity, spinning and flowing through you.