There is a close connection between evolution and yoga; it may even be said that the evolutionary process is basically a yogic process and that yoga is the conscious application of the processes of evolution and principles underlying those processes in order to accelerate the process of natural evolution. However, Yoga and its processes leave behind the ordinary tardy method of slow and confused growth through the evolution of Nature. As Sri Aurobindo points out: “The natural evolution is at its best an uncertain growth under cover, partly by the pressure of the environment, partly by a groping education, and an ill-lighted purposeful effort, an only partially illumined and half-automatic use of opportunities with many blunders and lapses and relapses; a great portion of it is made up of apparent accidents and circumstances and vicissitudes – though veiling a secret intervention and divine guidance. In yoga we replace this confused, crooked crab-motion by a rapid, conscious and self-directed evolution which is planned to carry us, as far as can be, in a straight line towards the goal set before us.”
There are, according to Sri Aurobindo, three stages in the process of evolution. An involution of the spirit in the inconscience is the beginning. Evolution in the ignorance with its play of possibilities of a partial developing knowledge is the middle. A consummation in a deployment of the spirit’s self-knowledge and self-power of its divine being and consciousness is the culmination. It is admitted that the two stages that have already occurred seem at first sight to deny the possibility of the later consummating state of the cycle, but it is stressed that logically they imply its emergence. For, it is argued, if the inconscience has evolved consciousness, the partial consciousness already reached much surely evolve into complete consciousness. It is contended that it is a supramentalised, perfected and divinised life for which the earth-nature is secretly seeking, and that a progressive manifestation of this kind can only have for its secret of significance the evolution of a Being in a perfect Becoming.
These three stages of evolution and the processes that can be observed in these stages can provide with us with a clue as to how the processes of evolution can be applied scientifically on the evolutionary process itself. This scientific application is the central principle of yoga.
 Sri Aurobindo: The Synthesis of Yoga, Vol. 18, Centenary Edition, p.83