The Buddhist word nirvana actually means to breathe out; letting go is the fundamental attitude of faith… Once we have surrendered a few times, we begin to incorporate the attitude of ‘letting go’ into our daily lives.
Grof argues that letting go is not a single crisis-event but a cumulative spiritual disposition — the very definition of faith — that deepens through repeated acts of surrender and builds trust in the benevolence of the deeper Self.
, The Thirst for Wholeness: Attachment, Addiction, and the Spiritual Path, 1993thesis