Sri Aurobindo's teaching starts from that of the ancient sages of India that behind the appearance of this universe there is the "Reality of a Being and Consciousness, a Self of all things, one and eternal". This "One Being and Consciousness", according to Sri Aurobindo, "is involved here in Matter. Evolution is the method by which it liberates itself."
Evolution is possible, Sri Aurobindo argued, only because the Divine has "involved" or "hidden himself" in the material universe at the beginning of creation. The "Superconscient Spirit" has involved himself in the "inconscient Matter" which gave birth to this material world. The seemingly inconscient Matter, therefore, is nothing but the Spirit in disguise. Evolution is the gradual unfoldment of this hidden spirit. Matter, Life, Mind, are nothing but different expressions of this Spirit at the different stages of evolution: the involved Divine through his creative energy gradually emerging in ever more conscious forms. The process of evolution will complete the circle with the manifestation of this hidden spirit, the involved Divine Reality in the material world.
. . . from the website of the Sri Aurobindo Ashram