Yoga is a science of spirituality that is deeply rooted in both psychology and metaphysics. In fact, it harkens back to the ancient, pre-Cartesian meaning of psychology - the study (logos) of the spirit (psyche). Yoga is not a religion. It is a vehicle for manifesting higher levels of consciousness that can, but need not be, directed at our chosen vision of God or Goddess.

Raja Yoga - sometimes referred to as Kriya Yoga - is regarded by scholars and practitioners alike as the one clear and direct tradition of realized saints and sages - the spiritual equivalent of self-actualization. The core of Raja Yoga is meditation, which itself is a highly exacting science of introspection aimed at exploring and developing the stages of consciousness.

Raja Yoga, the quintessence of all the yoga paths, incorporates the other main branches of yoga --- Hatha Yoga (physical discipline), Karma Yoga (good action), Mantra Yoga (chanting and incantation), Bhakti Yoga (devotion), Laya Yoga (ego integration) and Jnana Yoga (discriminative knowledge). These other paths, although valid in and of themselves, are considered side roads on the course to Self-realization, with only Raja Yoga being a direct path.

Mediation is the key to Self-realization, and success in meditation depends upon attention to the yamas and the niyamas, which are the first two limbs (yogangas) of ashtanga (eight limbed) Yoga, as described by the sage Patanjali in the Yoga Sutra. They are the heart of any intentional Yoga practice.

The yamas are the abstinences ("thou-must-nots") and are the fabric of ethical and moral behavior that we bring to our relationships and society at large. The niyamas are the observances ("thou-musts") and outline our relationship to ourselves.

Most important of the yamas is ahimsa or non-harming. Ahimsa refers to the cultivation of loving-kindness toward all beings, sentience and non-sentient. It is the rejection of aggression, violence and harmful thoughts, words, deeds and actions. Ahimsa encourages the development of compassion toward ourselves and for all our brothers and sisters, enemy or not.

The integration of the third and fourth limbs -- asana (postures) and pranayama (control of the vital energy (prana) via breath) -- is what is typically referred to as Hatha Yoga, and, historically, is considered to be the gift of Lord Shiva.

Hatha Yoga provides us with many benefits. The first is a strong body and radiant health. The second is flexibility and steadiness of mind, so that we may be successful in meditation. The third is the cultivation of breath, contributing to overall health, as well as the marriage of prana (life force) and apana (downward breath) through pranayama, which activates spiritual and psychological progression through the various levels of higher consciousness.

Although there are 5 pranas - prana, apana, samana, udana and vyana - prana and apana are considered the most important because it is their relationship that motivates spiritual and psychological development. Apana encompasses the physical body from the navel to the soles of the feet, and incorporates the first three chakra centers.

Muladhara chakra motivates us to get our basic needs of survival met. Swadisthana chakra is tied to feelings and emotion. Manipura chakra is our connection to sangha, or the larger community.

It is of considerable interest to note that the first three chakras correspond fairly directly to the basic stages of psycho-social development - egocentric, ethnocentric and geocentric, respectively. Most of us get stuck around the third and fourth (anahata) chakras - thinking about the bigger picture, but not acting upon, nor engaging with it.

With attention to the yamas and niyamas, supported by a consistent and intentional Hatha Yoga practice, we can begin to settle into the more esoteric aspects of Yoga sadhana - pratyahara (relinquishing attachments), dharana (concentration), dhyana (meditation) and samadhi (Self-realization/self-actualization).

Once we have mastered the ability to concentrate (dharana), to be still and focus in a mindful way, we can approach expansive awareness. Expansive awareness, or dhyana, is a mid level meditation. This is a state of meditation where we focus on the breath or an object of meditation and are able to maintain ourselves for an extended period.

Samadhi is the highest level of meditative consciousness, and it is only at this point that the meditator (the seer) and the object of meditation (the seen) become one. In Buddhist practice this is referred to as the loss of the ego. In Yoga it is referred to as the joining of Atman and Brahman. This state of realization is also the mystic vision of prophesy found in Christianity, Judaism, Islam and Sufism.

Through the practice of Yoga, and the mastery its various component limbs, we approach higher states of consciousness that can be brought back into our daily lives - Yoga off the mat. We can thus manifest a higher level of conscious awareness, compassion and spirituality which will, in turn, manifest for the people and relationships that surround us.

Most importantly, the practice of Yoga properly undertaken, whether complete or in part, will bring us a higher degree of Self-realization, self-actualization and, in some cases, a deeper connection to our chosen vision of God.