What is knowledge? And: How can we acquire knowledge? These are some of the questions that man has been seeking to answer for thousands of years and are the reason, that we have developed a vast spectrum of methods and techniques for obtaining knowledge, which include: science, meditation and the use of psychedelics. Today this subject is of particular relevance because the scientific and academic world has claimed patent to all real knowledge and truth. They have acquired the role as the keepers of knowledge, and therefore they are essentially dictating what is true and false. The problem with this is that knowledge is much more than conceptual and theoretical knowledge, which is what modern science, relies heavily on. According to the ancient spiritual traditions we have to go deeper than this form of knowledge in order to penetrate the mysteries of existence and the higher levels of consciousness. We have to understand it on all levels of our being. Apparently modern science is somehow satisfied with the more superficial conceptual and theoretical knowledge, but as the famous Indian yogi, Swami Sivananda, says: “One gram of practise is worth tons of theory”. This is especially valid when we are dealing with spiritual concepts and knowledge, where we easily can fall into philosophical speculations instead of practise and actually experience peak states directly. This lecture explores the relationship between science and spirituality and the challenges of researching peak experiences and higher states of consciousness within the scientific paradigm. It will illuminate these different aspects of knowledge and explore how we gain knowledge on all levels of our being. The lecture will present a unifying model of the mind and consciousness, based on the Tantric tradition and cognitive psychology and furthermore explore the different levels of consciousness.