In Śrī Vaiṣṇava theology, kaiṅkarya — loving, selfless service — is the very purpose and content of the liberated state. It is not merely a means to mokṣa but the essence of mokṣa itself: eternal joyful service to Bhagavān and Śrī in Śrīvaikuṇṭha. Within the realm of kaiṅkarya, ācārya kaiṅkaryam — service to one's Āchārya — is singled out by the Āchāryas as occupying the highest station in this world.
Piḷḷai Lokācārya explains in Śrīvacana Bhūṣaṇam (sūtras 398–430) that the Āchārya is the direct instrument through whom Bhagavān reaches the jīva. It is the Āchārya who initiates the disciple into the rahasya mantras, who provides the meaning of those mantras, and who, by his own grace, effects the prapanna's spiritual welfare. Because the Āchārya acts as Bhagavān's own representative — indeed, as the 'visible Bhagavān' (dṛṣṭa-devatā) — service to the Āchārya is equivalent to direct service to the Lord. The Āchārya's feet (āchārya pādukā) are worshipped as the supreme refuge.
The practical expression of ācārya kaiṅkaryam spans every dimension of life: physical service (attending to the Āchārya's personal needs), intellectual service (studying, preserving, and spreading his teachings), and emotional service (holding the Āchārya in the highest devotion and never causing him distress). The Āchāryas warn that the disciple must guard against allowing other loyalties — even Bhagavān-worship performed for personal benefit — to displace the primacy of the Āchārya relationship. This is the force behind Maṇavāḷa Māmunigaḷ's teaching that a life devoted to ācārya kaiṅkaryam is the highest sādhana available to a śiṣya in this world.