In Tantra one finds an amalgam of all four yoga. And there are three processes to Realize self through Sound ,the fundamental principle of the Universe and Abstract Thought. Mantras,Sounds, Yantra,Geometrical patterns to facilitate abstract thinking to still Chitta and Tantra, an amalgam of all yoga and the above two.
Urdhvaredham Viroopaaksham Viswaroopayay Namaha'-Narayna Suktham. At some point of time when Yoga is being practiced,when a practitioner is advancing,he shall have sexually stimulating visions,especially during Sakthi Upasna and he can advance only if he overcomes the stimulation and direct the flow upwards.
Though there are practices in Tantra where Yoni (females genital organ) and Male organ is worshipped and copulation is also practiced,one should know these practices do not have the sanction of the Vedas. 2.These practices are called Vaamachaara,the left handed path and are set aside by Acharyas like Adi Shankaracharya. 3. In practices indulged by one, he is beyond sensual pleasure and performs these acts with total detachment,fixing mind on Reality.This is a rare case.
There is Narayana Tantra which deals with Tantra. Even in this only basic aspect is referred. There is no elaborate description of Tantra Sri Vaishnavam. One finds elaborate description of Tantra aspects of Hinduism in Saivite texts, Shiva, Shakti,Ganapati,Subrahmanya. But this aspect is noticeably absent in Sri Vaishnavam.
And there is this accusation that Tantra is basically sex oriented and many indulge in it for Orgies. I have been meaning to write on Tantra as Password protected , paid articles to restrict access. I shall do so some time in future. In the mean while I was worried about some youngsters(Male and Female) asking me whether they can perform Yoni/Linga Pooja. I have decided to out line the outline what Tantra is.