The remainder of this Upanishad is supplementary, but contains several passages of considerable interest. We have here a cosmogonic myth, like those of the Brahmanas, in which the three qualities of matter, Tamas, Rajas, Sattva, are connected with Rudra, Brahma, and Vishnu, and which is in other respects very remarkable as a connecting link between the philosophy of the Rigveda and the later Sankhya system. The sun is further represented as the external, and prana (breath) as the internal, symbol of the Atman, their worship being recommended by means of the sacred syllable om, the three "utterances" (vyahritis) bhur, bhuvah, svar, and the famous Savitri stanza. As a means of attaining Brahma we find a recommendation of Yoga or the ascetic practices leading to a state of mental concentration and bordering on trance. The information we here receive of these practices is still undeveloped compared with the later system. In addition to the three conditions of Brahma, waking, dreaming, and deep sleep, mention is made of a fourth (turiya) and highest stage. The Upanishad concludes with the declaration that the Atman entered the world of duality because it wished to taste both truth and illusion. Older than the Maitrayana, which borrows from them, are two other Upanishads of the Black Yajurveda, the Kathaka and the Çvetaçvatara. The former contains some 120 and the latter some 110 stanzas. The Kathaka deals with the legend of Nachiketas, which is told in the Kathaka portion of the Taittiriya Brahmana, and a knowledge of which it presupposes. This is indicated by the fact that it begins with the same words as the Brahmana story. The treatise appears to have consisted originally of the first only of its two chapters. For the second, with its more developed notions about Yoga and its much more pronounced view as to the unreality of phenomena, looks like a later addition. The first contains an introductory narrative, an account of the Atman, of its embodiment and final return by means of Yoga. The second chapter, though less well arranged, on the whole corresponds in matter with the first. Its fourth section, while discussing the nature of the Atman, identifies both soul (purusha) and matter (prakriti) with it. The fifth section deals with the manifestation of the Atman in the world, and especially in man. The way in which it at the same time remains outside them in its full integrity and is not affected by the suffering of living beings, is strikingly illustrated by the analogy of both light and air, which pervade space and yet embrace every object, and of the sun, the eye of the universe, which remains free from the blemishes of all other eyes outside of it. In the last section Yoga is taught to be the means of attaining the highest goal. The gradation of mental faculties here described is of great interest for the history of the Sankhya and Yoga system. An unconscious contradiction runs through this discussion,