If we recognize that the Vedantic tradition focuses on the realisation and achievement of Knowledge through the various paths of Yoga, in most cases through the abandonment of the outer life in favor of the inner spiritual contemplation and Oneness, we quickly can discern the fundamental difference in approach taken by the Tantra, which uses the manifested Energy in Nature, Prakriti, as the means and focus of the tantric realisation.
Tantra recognised a deep truth that was mostly obscured in the other paths; namely, that Nature is real, and it provides us an access point to the deeper spiritual realisations. Sri Aurobindo describes the essence of the Tantric insight: “But in Tantra it is rather Prakriti, the Nature-Soul, the Energy, the Will-in-Power executive in the universe. It was by learning and applying the intimate secrets of this Will-in-Power, its method, its Tantra, that the Tantric Yogin pursued the aims of his discipline,–mastery, perfection, liberation, beatitude. Instead of drawing back from manifested Nature and its difficulties, he confronted them, seized and conquered.”
Along the way, Tantra ran into several issues that created the subsequent concerns about this path. The first of these was the proliferation of “techniques’ (as we also saw in the review of Hatha Yoga or Raja Yoga) which tended to overshadow the core principles over time. Second, and perhaps more importantly, the method chosen by the Tantra laid the practitioner open to various forms of self-deception caused by the fulfillment of desires, which diverted the attention from the true goal and attainments sought by the Tantra in the purity of its vision. This is what led to the later abuses of the “left handed path” and the disrepute in which many hold the Tantric tradition.
Nevertheless, if the goal is to achieve a true synthesis of yoga, and to realise our Oneness with the Divine, not only in some aloof “beyond” but also in the very forms and activities of life, the insights provided by Tantra are an important and valuable aspect which must be integrated.
Sri Aurobindo, The Synthesis of Yoga, Introduction: The Conditions of the Synthesis, Chapter 5, Synthesis, pg. 38