Compulsive thinking has become a collective disease. Your whole sense of who you are is then derived from mind activity. Your identity, as it is no longer rooted in Being, becomes a vulnerable and ever-needy mental construct, which creates fear as the predominant underlying emotion. The one thing that truly matters is then missing from your life: awareness of your deeper self—your invisible and indestructible reality.

Eckhart Tolle

from The Power of Now: A Guide to Spiritual Enlightenment