The yoga of works relies on turning all action into a sacrifice. But the esoteric sense of the outward action is based in the Oneness of all existence, where it is the Divine himself that carries out the sacrifice. A famous sloka of the Gita, frequently recited before taking food, conveys the sense of the integration of knowledge, works and devotion through the mystic Unity: “Brahman is the giving, Brahman is the food-offering, by Brahman it is offered into the Brahman fire, Brahman is that which is to be attained by Samadhi in Brahman-action.”
In the yoga of knowledge, the Divine is the knower, the knowledge and the object of knowledge. Knowledge is not intellectual, but experiential. The sacred Mantra carries the sound-body of the Divine and is the essence of knowledge. Sri Aurobindo describes this relationship: “The Mantra of the divine Consciousness brings its light of revelation, the Mantra of the divine Power its will of effectuation, the Mantra of the divine Ananda its equal fulfillment of the spiritual delight of existence. All word and thought are an outflowering of the great OM,–OM, the Word, the Eternal. Manifest in the forms of sensible objects, manifest in that conscious play of creative self-conception of which forms and objects are the figures, manifest behind in the self-gathered superconscient power of the Infinite, OM is the sovereign source, seed, womb of thing and idea, form and name,–it is itself, integrally, the supreme Intangible, the original Unity, the timeless Mystery self-existent above all manifestation in supernal being.”
There is a unification of the yoga of works, the yoga of knowledge and the yoga of devotion in the mystic revelation of OM.
OM has been described and lauded in the Upanishads and there are those who hold that OM is the secret sound of all the collective sounds of the entire Universe.
The Mandukya Upanishad defines it thus: “AUM,–A the spirit of the gross and external, Virat, U the spirit of the subtle and internal, Taijasa, M the spirit of the secret superconscient omnipotence, Prajna, OM the Absolute, Turiya”
Sri Aurobindo, Essays on the Gita, Second Series, Part I, Chapter 6, Works, Devotion and Knowledge, pp. 314-315
Sri Aurobindo, Bhagavad Gita and Its Message, page 82, Chapter IV, Sloka 24