Chandogya Upanishad 6.2

'In the beginning,' my dear, "there was that only which is (τὸ ὄν), one only, without a second. Others say, in the beginning there was that only which is not (τὸ μὴ ὄν), one only, without a second; and from that which is not, that which is was born.

'But how could it be thus, my dear?' the father continued. 'How could that which is, be born of that which is not? No, my dear, only that which is, was in the beginning, one only, without a second.

'It thought may I be many, may I grow forth. It sent forth fire. 'That fire thought, may I be many, may I grow forth. It sent forth water. 'And therefore whenever anybody anywhere is hot and perspires, water is produced on him from fire alone.

'Water thought, may I be many, may I grow forth. It sent forth earth (food). 'Therefore whenever it rains anywhere, most food is then produced. From water alone is eatable food produced.