Accordingly the Brahmavadin concerns himself not only with the theory as to the nature of the Absolute, but also with the development of the faculty by which to come face to face with It. While logically establishing the nature of Brahman by an elaborate course of metaphysical argument, the Vedanta describes in some detail the process of purifying the mind or Manas as it is called. As Manas is purged of its dross, of its desires for and attachment to earthly and celestial pleasures, it loses its fickleness and tends to become steady. On attaining to a state of perfect steadiness, it ceases to be what it now appears to be and becomes one with Brahman; and this unity of Manas with Brahman is what is called Brahma-Sakshatkara, an intuitive or immediate cognition of Brahman. Nothing short of the Sakshatkara can produce an absolute conviction as to what the Thing in itself is.