And what exactly Vedas say about Tantric Philosophy?
Precisely! Are they completely different or Are they talking about the same thing? Truth can be explored in multiple ways. You could say Today’s Hinduism is seemingly based out of Brahministic and Vedic roots, as, that’s what probably our parents, society and ancestors /traditions taught you. The reiterated propaganda machinery of Vedas, Puranas through generations put solid foundations of the Vedic deities their greatness and their valour and courage and their Success stories and how that relate to us and our well-being by following it piously, ritualistically and practicing it while following worldly life and the goal being to attain Moksha. The myriad of Tantric based word-of-mouth suggested yet another path for a Sadhu life who sacrifices Worldly things and hence Deva propitiation is not needed and also to take up full time the quest for Truth / Brahman and in a way helping others in similar paths. Vedas explored Pancha bootha based body’s well-being by propitiating appropriate deities that are responsible for it. Like Savitr, Soma, Indra, Varuna, Rudra, Usas. Brhaspati, Mitra, Soorya etc. These deities are the ones running you as a whole day in and day out and they do require those propitiations for their satisfaction so your life is better. But, among these propitiation mantras in the Vedas, some gems were studded indicating and hinting as to the real truth. The truth/knowledge trickled through in Nasdaya Sukta and Sama Veda Agneya Kanda, In rig Veda Purusha Sukta etc. and of course the ‘sit beside sessions’ of the Upanishads and Brahma sutras. Here is an example
"In ancient times in the early morning of creation, in the beginning, the effulgent consciousness bestowed his rays to look within( in the head), from beyond, which kindled the waking state by uniting(with the brain)"
Sama veda, Agneya Kanda, chapter 1, verse 20
“Then there was neither death nor immortality
nor was there then the torch of night and day.
The One breathed windlessly and self-sustaining.
There was that One then, and there was no other.”
“But, after all, who knows, and who can say
Whence it all came, and how creation happened?
the devas (gods) themselves are later than creation,
so who knows truly whence it has arisen?”
Both from Nasadaya Sukta. Now, if the devas came later, then Propitiation of them in Vedas comes later as well. But then prior to Vedas what/ or who were the primordial Gods? Whence Brahman ( not Brahma) thought came to be? Shaivism/ Tantrism explored these quite a bit prior to Vedas. The primordial Gods were Shiva and Shakti or Purusha ( still) and Prakriti (active). The Tantric books were based out of Shakti knowledge paths from books called ShatchakraNirupana, Varivasya Rahasya etc. which is the basis for Lalitha Sahasranamam, Kundalini yoga etc. check out the book the ‘The Serpent Power’ by Sir Arthur Avalon. He took great pains in 1930s to get the Knowledge out of West Bengal Pandits. It is still steeped in secrecy. Shaivism is from Shiva word of mouth either through Nandi or Shiva to Shakti or From Shiva himself. The Shiva knowledge is in the form of Agamas which is main stream Shaivism and Kashmiri Shaivism. Kashmiri Shaivism is a set of Tantric philosophies( not exactly Kularnava Tantra and the likes) from Saint Vasugupta which deals with identity of the Individual self with the divine according to tribal knowledge. There are a set of five books that you could get hold of in Amazon. There is an order to read them.
Vijnanabhairava, Pratyabhijnahrdyam, Siva Sutras, Para trisika Vivarana and Spanda Karika. Most of this was by word of mouth until early 1900s when Abhinav Gupta put it in writing. You could compare them to Upanishads but I could say for Kundalini Awakened aspirants this might relate more to their experience mainly in Spanda Karika. As you know, Hinduism is not really entirely Theory, there is Practice and finally an ‘Experience’ aspect. Kashmiri Shaivism is a philosophy for the experience and hence not that popular in common discussions and the subject is considered dense. Now, I have read through couple of them and skimmed through the rest, I don’t think there’s any statement with respect to Indra, Agni and Soma etc. there. There is a Sutra from Vasu Gupta at the end that says ‘please keep this secret as well’.
The original purport and reasoning for this is known only to a few still.