What is the experience of not-self?
The experience of not-self is the awareness of pure consciousness. Pure consciousness is not personal, it is not my consciousness or your consciousness. Pure consciousness is the essence of reality; is not born nor does it die; is permanent, eternal and boundless.
Pure consciousness is distinct from the contents of experience; pure consciousness is the screen on which the contents of consciousness appears. The contents of consciousness includes gross and subtle experiences: the five clinging aggregates which constitute the empirical being (form, thoughts, perceptions, feelings and sensory consciousness). Contents of consciousness are impermanent, cause suffering and are not-self.
Some of the characteristics of pure consciousness are wisdom, loving-kindness and happiness. Wisdom includes such knowledge as: the characteristics of the ego or personality, the impermanent nature of the world and body, and the cause and escape from suffering. Loving-kindness is the felt understanding that the essence, pure consciousness, is identical in all beings, and therefore, all beings are in essence not separated from each other but are one with all of reality. Happiness is the experience of being free of the suffering ego, it is the experience of great peace.
Mindfulness and concentration are the mental faculties utilized to make the distinction between pure consciousness and the contents of consciousness.