Series 1, Chapter 10 pg 96, Para 1: speaking, the mental power of understanding but it is evidently used by the Gita in a large philosophic sense for the whole action of the discriminating and deciding mind which determines both the direction and use of our thoughts and the direction and use of our acts; thought, intelligence, judgment, perceptive choice and aim are all included in its functioning: for the characteristic of the unified intelligence is not only concentration of the mind that knows, but especially concentration of the mind that decides and persists in the decision, vyavasaya, while the sign of the dissipated intelligence is not so much even discursiveness of the ideas and perceptions as discursiveness of the aims and desires, therefore of the will. Will, then, and knowledge are the two functions of the Buddhi. The unified intelligent will is fixed in the enlightened soul, it is concentrated in inner self-knowledge; the many-branching and multifarious, busied with many things, careless of the one thing needful is on the contrary subject to the restless and discursive action of the mind, dispersed in outward life and works and their fruits. “Works are far inferior,” says the Teacher, “to Yoga of the intelligence; desire rather refuge in the intelligence; poor and wretched souls are they who make the fruit of their works the object of their thoughts and activities.”

Series 1, Chapter 10 pg 99, Para 2: Therefore, it is the upward and inward orientation of the intelligent will that we must resolutely choose with a settled concentration and perseverance, vyavasaya; we must fix it firmly in the calm self-knowledge of the Purusha. The first movement must be obviously to get rid of desire which is the whole root of the evil and suffering; and in order to get rid of desire, we must put an end to the cause of desire, the rushing out of the senses to seize and enjoy their objects. We must draw them back when they are inclined thus to rush out, draw them away from their objects, — as the tortoise draws in his limbs into the shell, so these into their source, quiescent in the mind, the mind quiescent in intelligence, the intelligence quiescent in the soul and its self-knowledge, observing the action of Nature, but not subject to it, not desiring anything that the objective life can give.