Tantra is a vast subject. Scholars are still unsure if tantra arose from yoga or yoga developed from tantra. In either case, it was part of a world-wide recognition over several centuries of a unitary reality higher than the currents of everyday life. Polytheism gave way to something higher. In the West monotheism flourished, in the East the concept of a unified reality was laid on top of, and subsumed, a patchwork of religious deities.
If you work away the cultural baggage and elaboration, tantra has a few simple things to say:
- This is it; the world is perfectly real
- all of reality is vibrating (spanda) and conscious
- humans are never disconnected from the universe
- you can improve the connection greatly.