Tāraka-mantra — The Mantra That Saves
"Tāraka" is derived from the Sanskrit verbal root tṝ, meaning to cross, to go beyond, to be delivered from. The tāraka-mantra is therefore the mantra that enables the jīvātman to cross the vast and turbulent ocean of saṃsāra — the cycle of birth, death, and rebirth conditioned by karma and ignorance. The designation carries the sense of rescue and deliverance.
In Śrī Vaiṣṇava siddhānta, the Dvayam ("Śrīman Nārāyaṇa-caraṇau śaraṇaṃ prapadye / Śrīmate Nārāyaṇāya namaḥ") is regarded as the Tāraka-mantra par excellence. Unlike the Aṣṭākṣara, which primarily declares the relationship of the self to Bhagavān, and the Carama-śloka, which is Bhagavān's own promise of protection, the Dvayam is the devotee's act of surrender (prapatti) combined with the expression of purpose — eternal service to Bhagavān along with Śrī (Lakṣmī-Pirāṭṭi). It thus constitutes both the means (upāya) and the goal (upeya) in a single utterance.
Piḷḷai Lokācārya's Mumukṣuppāḍi (the definitive Śrī Vaiṣṇava commentary on the three Rahasya-mantras) devotes the majority of its verses to explaining the Dvayam, reinforcing its status as the Tāraka-mantra. The constant, meditative repetition of the Dvayam is taught as the highest spiritual practice for the prapanna — a practice that itself constitutes the experience of the soul's true svarūpa as a servant of the Divine Couple.