As with ātman and brahman, the aim in yoga is to unite with the larger essence of the universe (Purusha, the spiritual side of the world).
So, we can see a common mindset in all these Indic practices: (1) Vedic--realizing the unity of ātman with brahman (brings eternal joy or moksha), (2) yogic--returning from individual (separate) consciousness to the universal spirit (resulting in eternal bliss or moksha), and (3) Tantric--union of the universal divine within one’s individual body.