These philosophical developments shaped the evolution of yoga. The Upanishads of around the 7th century BCE marked the beginning of a new thought, for they introduced into the world such concepts as Samsara – the cycle of birth, death, and rebirth – and Karma – the belief that actions have consequences extending beyond one lifetime. These had to form part of the formation of yoga because they held the promise of liberation only through the transcendence of the cycles of reincarnation.

By the 5th century BCE, yoga developed into more defined styles. The Bhagavad Gita, a scripture completed by the end of the first millennium, provides key concepts of yoga practice that remain influential today. In scripture, yoga is described in three primary forms: Karma Yoga-the yoga of selfless action, Bhakti Yoga-the yoga of devotion, and Jnana Yoga-the yoga of wisdom. These practices therefore opened yoga to wider sections of population, suggesting one need not abandon the world or seek isolation to aim at spiritual development.

The form of yoga as we know it today began to take shape sometime during Patanjali’s Yoga Sutras. Patanjali, whose work was written in the second century CE, formalized yoga into a set of eight steps or limbs, each known as Ashtanga Yoga. These practices describe a process of spiritual and physical development that ultimately leads to Samadhi – an experience of unalloyed, transcendent union with the divine. The definition of yoga formul

Influenced by Patanjali, around the 6th century CE, Tantric Yoga took its form. A system of thought that emphasized rituals, mantras, and visualization, Tantra emerged as a philosophy in an attempt to see divine in everything, body and all, and thus merged the dualistic aspects that the previously existing schools of thought-differentiated in most instances the illusory material world from the reality. Thus, for Tantrics, the practice became integrating the spiritual and the physical because these aspects of life cannot be separated.

At such a time, in the 8th century, there lived the philosopher Adi Shankaracharya who propagated the philosophy of Advaita Vedanta, one of the earliest schools of Indian thought, in which great emphasis was placed on the doctrine of non-duality-that indeed all of reality is one and that this ultimate truth is in the experience of the oneness of the self with the universe. Shankaracharya’s teachings have influenced many different schools of Indian thought, including the Tantric traditions, in which there has been considerable interest in the nature of consciousness and the interconnectedness of all things.

On the other hand, Kashmir Shaivism, dating back to the 8th century, is much more substantial. This stream of thought perceives the world as an expression of the only one ultimate reality. In reality, this philosophy perceives the universe not as an illusion but as the manifestation of divine energy; yoga is a way to remember one’s original power and unity with the divine source. Kashmir Shaivism is even more sensate, in that yoga occurs within the world, not apart from it.

Today, these varied manifestations of yoga philosophy continue to guide how practitioners go about the practice. Those early mystical insights of the Upanishads, these more practical disciplines of Patanjali, even the devotional elements of the Bhagavad Gita-all have led to this rich multifaceted discipline: understanding and navigating the complexities of life, mind, and spirit as a depth of inner journey and an outer path of service and connection to others.