So 'by wisdom' it is said 'one gets immortality.' The Spirit develops gradually in man; by means of the mortal he desires the immortal; whereas other animals have only hunger and thirst as a kind of understanding, and they are reborn according to their knowledge as beasts again. Such is the teaching of another of the Upanishads, the [=A]itareya [=A]ranyaka.
This Upanishad contains some rather striking passages: "Whatever man attains, he desires to go beyond it; if he should reach heaven itself he would desire to go beyond it" (2. 3. 3. 1). "_Brahma_ is the A, thither goes the ego" (2. 3. 8. 7). "A is the whole of Speech, and Speech is Truth, and Truth is Spirit" (2. 3. 6. 5-14).[16] "The Spirit brooded over the water, and form (matter) was born" (2. 4. 3. 1 ff.); so physically water is the origin of all things" (2. 1. 8. 1).[17] "Whatever belongs to the father belongs to the son, whatever belongs to the son belongs to the father" (_ib_.). "Man has three births: he is born of his mother, reborn in the person of his son, and finds his highest birth in death" (2. 5).
In the exposition of these two Upanishads one gets at once the sum of them all. The methods, the illustrations, even the doctrines, differ in detail; but in the chief end and object of the Upanishads, and in the principle of knowledge as a means of attaining _brahma_, they are united. This it is that causes the refutation of the Vedic 'being from not-being.' It is even said in the [=A]itareya that the gods worshipped breath (the spirit) as being and so became gods (great); while devils worshipped spirit as not-being, and hence became (inferior) devils (2. 1. 8. 6).
It was noticed above that a king instructed priests. This interchange of the rôles of the two castes is not unique. In the K[=a]ush[=i]taki Upanishad (4. 19), occurs another instance of a warrior teaching a Brahman. This, with the familiar illustration of a Gandh[=a]ra (Kandahar) man, the song of the Kurus, and the absence of Brahmanic literature as such in the list of works, cited vii. 1, would indicate that the Ch[=a]ndogya was at least as old as the Br[=a]hmana literature.[18]
In their present form several differences remain to be pointed out between the Vedic period and that of the Upanishads. The goal of the soul, the two paths of gods and of _brahma_, have been indicated. As already explained, the road to the absolute _brahma_ lies beyond the path to the conditioned _brahma_. Opposed to this is the path that leads to the world of heaven, whence, when good works have been exhausted, the spirit descends to a new birth on earth. The course of this second path is conceived to be the dark half of the moon, and so back to man. Both roads lead first to the moon, then one goes on to _brahma_, the other returns to earth. It will be seen that good works are regarded as buoying a man up for a time, till, like gas in a balloon, they lose their force, and he sinks down again. What then becomes of the virtue of a man who enters the absolute _brahma,_ and descends no more? He himself goes to the world where there is "no sorrow and no snow," where he lives forever (_Brihad [=A]ran_. 5. 10); but "his beloved relations get his virtue, and the relations he does not love get his evil" (_K[=a]ush[=i]t. Up_. 1. 4). In this Upanishad fire, sun, moon, and lightning die out, and reappear as _brahma_. This is the doctrine of the _Götterdämmerung_, and succession of aeons with their divinities (2. 12). Here again is it distinctly stated that _pr[=a]na_, breath, is _brahma_; that is, spirit is the absolute (2. 13).