In other words, purification must not be understood in any limited sense of a selection of certain outward kinetic movements, their regulation, the inhibition of other action or a liberation of certain forms of character or particular mental and moral capacities. These things are secondary signs of our derivative being, not essential powers and first forces. We have to take a wider psychological view of the primary forces of our nature. We have to distinguish the formed parts of our being, find out their basic defect of impurity or wrong action and correct that, sure that the rest will then come right naturally. We have not to doctor symptoms of impurity, or that only secondarily, as a minor help, — but to strike at its roots after a deeper diagnosis. We then find that there are two forms of impurity which are at the root of the whole confusion. One is a defect born of the nature of our past evolution, which has been a nature of separative ignorance; this defect is a radically wrong and ignorant form given to the proper action of each part of our instrumental being. The other impurity is born of the successive process of an evolution, where life emerges in and depends on body, mind emerges in and depends on life in the body, supermind emerges in and lends itself to instead of governing mind, soul itself is apparent only as a circumstance of the bodily life of the mental being and veils up the spirit in the lower imperfections. This second defect of our nature is caused by this dependence of the higher on the lower parts; it is an immixture of functions by which the impure working of the lower instrument gets into the characteristic action of the higher function and gives to it an added imperfection of embarrassment, wrong direction and confusion.
Thus the proper function of the life, the vital force, is enjoyment and possession, both of them perfectly legitimate, because the Spirit created the world for Ananda, enjoyment and possession of the many by the One, of the One by the many and of the many too by the many; but, — this is an instance of the first kind of defect, — the separative ignorance gives to it the wrong form of desire and craving which vitiates the whole enjoyment and possession and imposes on it its opposites, want and suffering. Again, because mind is entangled in life from which it evolves, this desire and craving get into the action of the mental will and knowledge; that makes the will a will of craving, a force of desire instead of a rational will and a discerning force of intelligent effectuation, and it distorts the judgment and reason so that we judge and reason according to our desires and prepossessions and not with the disinterested impartiality of a pure judgment and the rectitude of a reason which seeks only to distinguish truth and understand rightly the objects of its workings. That is an example of immixture. These two kinds of defect, wrong form of action and illegitimate mixture of action, are not limited to these signal instances, but belong to each instrument and to each combination of their functionings. They pervade the whole economy of our nature. They are fundamental defects of our lower instrumental nature, and if we can set them right, we shall get our instrumental being into a state of purity, enjoy the clarity of a pure will, a pure heart of emotion, a pure enjoyment of our vitality, a pure body. That will be a preliminary, a human perfection, but it can be made the basis and open out in its effort of self-attainment into the greater, the divine perfection.
— Sri Aurobindo, The Synthesis of Yoga, p. 645-46
Some further details on how to make the mind function better are here: