The Zen meditative approach has a simple, unstated premise: moods and attitudes shape—determine—what we think and perceive. If we feel happy, we tend to develop certain trains of thought. If we feel sad or angry, still others. But suppose, with training, we become nonattached to distractions and learn to dampen these wild, emotional swings on either side of equanimity. Then we can enter that serene awareness which is the natural soil for positive, spontaneous personal growth, often called spiritual growth.
James H. Austin (1999). “Zen and the Brain: Toward an Understanding of Meditation and Consciousness”, p.13, MIT Press