Sri Aurobindo
Letters of Sri Aurobindo
Volume II - Part 3
The Vedic Rishis were mystics of the ancient type who everywhere, in India, Greece, Egypt and elsewhere, held the secret 
truths and methods of which they were in possession as very sacred and secret things not to be disclosed to the unfit who would misunderstand, misapply, misuse and degrade the knowledge. Their writings were therefore so couched as only to be intelligible in their secret meaning to the initiated, niṇyā vacāṃsi nivacanāni kavaye – secret words that carry their significance only to the seer. They were equipped with an apparent meaning exoteric and religious for the people, esoteric, occult and spiritual for the initiates. That the people should not find out the real Truth was their intention; they wanted them only to know the outward truths for which they were fit.