The Upanishads, Part 2 (SBE15), by Max Müller, [1879], at sacred-texts.com
1. There are two forms of Brahman, the material and the immaterial, the mortal and the immortal, the solid and the fluid, sat (being) and tya (that), (i.e. sat-tya, true) 2.
2. Everything except air and sky is material, is mortal, is solid, is definite. The essence of that which is material, which is mortal, which is solid, which is definite is the sun that shines, for he is the essence of sat (the definite).
3. But air and sky are immaterial, are immortal, are fluid, are indefinite. The essence of that which is immaterial, which is immortal, which is fluid, which is indefinite is the person in the disk of the sun, for he is the essence of tyad (the indefinite). So far with regard to the Devas.
4. Now with regard to the body. Everything except the breath and the ether within the body is material, is mortal, is solid, is definite. The essence of that which is material, which is mortal, which is solid, which is definite is the Eye, for it is the essence of sat (the definite).
5. But breath and the ether within the body are immaterial, are immortal, are fluid, are indefinite. The essence of that which is immaterial, which is immortal, which is fluid, which is indefinite is the person in the right eye, for he is the essence of tyad (the indefinite).
6. And what is the appearance of that person? Like a saffron-coloured raiment, like white wool,
like cochineal, like the flame of fire, like the white lotus, like sudden lightning. He who knows this, his glory is like unto sudden lightning.
Next follows the teaching (of Brahman) by No, no 1! for there is nothing else higher than this (if one says): 'It is not so.' Then comes the name 'the True of the True,' the senses being the True, and he (the Brahman) the True of them.
107:1 Mâdhyandina text, p. 1062.
107:2 Sat is explained by definite, tya or tyad by indefinite.
108:1 See III, 9, 26; IV, 2,4; IV, 4, 22; IV, 5, I5.