There are two main traditions of kriya yoga in the world today: Paramahamsa Yogananda’s tradition and Swami Sivananda’s tradition. Paramahamsa Yogananda’s is a simplified version of kriya yoga. Not all the techniques or theories are taught because the entire concept of kriya yoga, energy and chakras can become too complex to grasp. So they teach a simplified version which is very effective, but not complete. It takes you to a point where
you can get in touch with your internal energies. The kriya yoga of Swami Sivananda, as developed by Swami Satyananda, is the classical, unmodified kriya yoga that has been taught in the tradition throughout the ages. The purpose of kriya yoga is the synthesis of all the yogas; there are components of hatha yoga, raja yoga, kundalini yoga.
Our body and mind are not yet adapted to practise this kriya yoga. Before starting kriya yoga, first you need to perfect hatha yoga, then you need to achieve a certain state in raja yoga, mind management, so that as you practise kriya yoga and psychic experiences begin to happen, you are able to handle them more efficiently, effectively and easily, and to understand them. Each experience of kriya yoga is a map of your spiritual journey. Therefore, kriya yoga has always been treated as a sacred and secret subject, mainly because our non-transcendental brain is incapable of experiencing the transcendental reality. So, before practising kriya yoga, practise the other yogas to change your non-transcendental brain into a transcendental brain.
—International Yoga Convention, 20–22 May 2005, Bogota, Colombia