All emanations of the fountainhead are also complete in themselves, but although many complete units emanate from the complete sanātana fountainhead, the sanātana head does not diminish in quality or quantity.* That is because the nature of sanātana is unchangeable. Anything that changes under the influence of time and circumstances is not sanātana. Therefore anything that changes whatsoever in form or quality cannot be accepted as sanātana. To give a material example, the sun has been disseminating its rays for hundreds and millions of years, and yet although it is a materially created object, its form and rays are still unchanged. Therefore, that which is never created cannot change in formation and quality, even though He is the seedling source of everything.
The Lord claims to be the father of all species of life. He claims that all living beings—regardless of what they are—are part and parcel of Him. Consequently, the Bhagavad-gītā is meant for all of them. In the Gītā there is information of this sanātana nature of the Supreme Lord. There is also information of His abode, which is far beyond the material sky, and of the sanātana nature of the living beings.