The secret practice in upanishads and tantra

There are 18 Yogopanishads and all of them talk about Sohum meditation as an important meditation of salvation.

As per vedanta upanishads also union of "sah" (paramatma) and aham (jeevathma) is "sohum" which helps to reach the ultimate.

In Tantra 'sa' is the beejakshara of "Shakthi" and 'ha' is the beejakshara of "Shiva". So the union of Shakthi and Shiva is "Sohum". We can say this in science as the union of matter and energy.

As per all the darshanas and shastras including thantra, sohum is the ultimate meditation.

So do this practice daily.