When we speak of sanātana-dharma, therefore, we must take it for granted on the authority of Śrī Rāmānujācārya that it has neither beginning nor end.
Bhagavad-gītā As It Is -1972: introduction
Śrīla Rāmānujācārya writes in his book Vedānta-saṅgraha: (about Varṇāśrama)
evaṁ-vidha-parābhakti-svarūpa-jñāna-viśeṣasyotpādakaḥ pūrvoktāharahar upacīyamāna-jñāna-pūrvaka-karmānugṛhīta-bhakti-yoga eva; yathoktaṁ bhagavatā parāśareṇa—varṇāśrameti. nikhila-jagad-uddhāraṇāyāvanitale 'vatīrṇaṁ para-brahma-bhūtaḥ puruṣottamaḥ svayam etad uktavān—"svakarma-nirataḥ siddhiṁ yathā vindati tac chṛṇu" "yataḥ pravṛttir bhūtānāṁ yena sarvam idaṁ tatam / svakarmaṇā tam abhyarcya siddhiṁ vindati mānavaḥ"
To defeat this kevalādvaita-vāda, Śrī Rāmānujācārya presented his philosophy as viśiṣṭādvaita-vāda.
Śrī Caitanya-caritāmṛta Ādi 7.110
Nondevotees factually appreciate the wonderful creation of material nature, but they cannot appreciate the intelligence and energy of the Supreme Personality of Godhead who is behind this material creation. Śrīpāda Rāmānujācārya, however, refers to a sūtra from the Aitareya Upaniṣad (1.1.1), ātmā vā idam agra āsīt, which points out that the supreme ātmā, the Absolute Truth, existed before the creation. One may argue, "If the Supreme Personality of Godhead is completely spiritual, how is it possible for Him to be the origin of creation and have within Himself both material and spiritual energies?"
To answer this challenge, Śrīpāda Rāmānujācārya quotes a mantra from the Taittirīya Upaniṣad (3.1) that states:
yato vā imāni bhūtāni jāyante yena jātāni jīvanti yat prayanty abhisaṁviśanti
This mantra confirms that the entire cosmic manifestation emanates from the Absolute Truth, rests upon the Absolute Truth and after annihilation again reenters the body of the Absolute Truth, the Supreme Personality of Godhead. The living entity is originally spiritual, and when he enters the spiritual world or the body of the Supreme Lord, he still retains his identity as an individual soul. In this connection Śrīpāda Rāmānujācārya gives the example that when a green bird enters a green tree it does not become one with the tree: it retains its identity as a bird, although it appears to merge in the greenness of the tree. To give another example, an animal that enters a forest keeps its individuality, although apparently the beast merges in the forest. Similarly, in material existence, both the material energy and the living entities of the marginal potency maintain their individuality. Thus although the energies of the Supreme Personality of Godhead interact within the cosmic manifestation, each keeps its separate individual existence. Merging in the material or spiritual energies, therefore, does not involve loss of individuality. According to Śrī Rāmānujapāda's theory of Viśiṣṭādvaita, although all the energies of the Lord are one, each keeps its individuality (vaiśiṣṭya).
Śrī Caitanya-caritāmṛta Ādi 7.121
Śrīpāda Rāmānujācārya, in his Vedārtha-saṅgraha, says: jñānena dharmeṇa svarūpam api nirūpitam, na tu jñāna-mātraṁ brahmeti katham idam avagamyate. He thus indicates that the real absolute identity must be understood in terms of both His knowledge and His characteristics. Simply to understand the Absolute Truth to be full of knowledge is not sufficient.
Śrī Caitanya-caritāmṛta Ādi 7.140
This Kūrma-sthāna is a well-known place of pilgrimage. There is a temple there of Kūrmadeva. In the Prapannāmṛta it is said that Lord Jagannātha took Śrī Rāmānujācārya from Jagannātha Purī and one night threw him to Kūrma-kṣetra. This Kūrma-kṣetra is situated on the line of the Southern Railway in India. One has to go to the railway station known as Cikā Kola Road. From this station one goes eight miles to the east to reach the holy place known as Kūrmācala. Those who speak the Telugu language consider this holy place very important. This statement is reported in the government gazette known as Gañjāma Manual. There is the Deity of Kūrma there, and Śrīla Rāmānujācārya was thrown from Jagannātha Purī to this place. At that time he thought that the Deity of Kūrma was Lord Śiva's deity; therefore he was fasting there. Later, when he understood that the kūrma-mūrti was another form of Lord Viṣṇu, he instituted very gorgeous worship of Lord Kūrma. This statement is found in the Prapannāmṛta (Chapter Thirty-six). This holy place of Kūrma-kṣetra, or Kūrma-sthāna, was actually reestablished by Śrīpāda Rāmānujācārya under the influence of Lord Jagannātha-deva at Jagannātha Purī.
Śrī Caitanya-caritāmṛta Madhya 7.113
In this connection, Śrī Rāmānujācārya stated in the Vedārtha-saṅgraha that devotional service is naturally very dear to the living entity. Indeed, it is life's goal. This devotional service is supreme knowledge, or Kṛṣṇa consciousness, and it brings detachment from all material activity.
Śrī Caitanya-caritāmṛta Madhya 8.57