Maitrāyaṇīya Āraṇyaka 6.3

Two indeed are the forms of Brahman: the formed and the unformed. Now that which is formed is unreal; that which is unformed is real. That is Brahman; that is light. That which is light is the sun. And he indeed became the self consisting of this: 'Oṃ.' He divided himself threefold, for 'Oṃ' has three morae; by these 'all this is woven warp and woof in me'—for so he said. One should join the Self in meditation thinking thus: 'The sun is Oṃ.'

Now it has also been said elsewhere: 'Now indeed, that which is the udgītha is the Praṇava; that which is the Praṇava is the udgītha.'

That sun is the udgītha; he is the Praṇava, for so he said: 'The udgītha, named the Praṇava,

the leader, having the form of light, free from sleep, free from old age, free from death, three-footed, of three syllables, yet again to be known fivefold,

deposited in the secret cave'—for so he said. 'With root above is the three-footed Brahman; the branches

are space, wind, fire, water, earth, and the rest. This single Brahman bears the name of the sacred fig tree (aśvattha). Its splendor is that