Since Yoga aims to achieve realization of union with the Divine in a higher status of consciousness, not just an intellectual conviction or emotional attachment to a specific form or religious belief, it must necessarily involve methods for developing the consciousness on the higher levels. We have seen that Samadhi is a powerful tool for the individual to experience the higher planes and for some forms of Yoga, attainment of Samadhi is tantamount to success in the practice, as it achieves the Oneness that the seeker is trying to achieve.
The status of the yogic trance however can be achieved through all the paths of Yoga, not solely through the practices known under the general rubric of the Yoga of knowledge, although clearly it occupies a central role in that yogic path. There can be the ecstatic trance of the devotional paths, for instance. And there are the paths involving psycho-physical practices that can lead to Samadhi as well. The most well-known of these are called Hatha Yoga and Raja Yoga.
Sri Aurobindo observes: “…for in spite of the wide difference of their methods from that of the path of knowledge, they have this same principle as their final justification. At the same time, it will not be necessary for us to do more than regard the spirit of their gradations in passing; for in a synthetic and integral Yoga they take a secondary importance; their aims have indeed to be included, but their methods can either altogether be dispensed with or used only for a preliminary or else a casual assistance.”
The integral Yoga may, at various stages, utilize the techniques or practices of any of the paths of Yoga, but it is not bound to them. The seeker will deal with the various complex aspects of his nature using whatever tools are necessary, while keeping his focus on the end goal of union with the Divine and the transformation of his life and action in the world. The intense and all-consuming concentration required for ultimate success in the practice of Hatha Yoga cannot be more than a brief interlude in this wider aspiration.
Sri Aurobindo, The Synthesis of Yoga, Part Two: The Yoga of Integral Knowledge, Chapter 27, Hathayoga, pp. 506-507