Claudio Naranjo and Robert E. Ornstein's 1971 book, On the Psychology of Meditation, presents a comprehensive synthesis of various meditation techniques from ancient spiritual traditions—such as Zen, Yoga, Sufism, and shamanism—and examines them in light of modern psychology and science, particularly neuropsychology. The book explores the potential and relevance of these findings for contemporary needs, showing how an understanding of the psychology of meditation can be used for personal growth and healing, beyond traditional religious contexts. Overall, this in-depth exploration of the mental and neurological mechanisms behind the meditative experience integrates ancient wisdom with modern scientific insights to understand the hidden potential of the human mind. The authors also discuss how various meditation practices affect the brain and psychological functioning. Modern research related to the book's ideas suggests that meditation, particularly mindfulness, can induce structural changes in the brain associated with emotion regulation, self-awareness, and the processing of negative emotions.