Five hundred years ago the condition of society was not as degraded as it is today. At that time people would show respects to a sannyāsī, and the sannyāsī was rigid in following the rules and regulations of the renounced order of life. Śrī Caitanya Mahāprabhu was not very much in favor of the renounced order of life in this age of Kali, but that was only for the reason that very few sannyāsīs in this age are able to observe the rules and regulations of sannyāsa life. Śrī Caitanya Mahāprabhu decided to accept the order and become an ideal sannyāsī so that the general populace would show Him respect. One is duty-bound to show respect to a sannyāsī, for a sannyāsī is considered to be the master of all varṇas and āśramas.
While He was contemplating accepting the sannyāsa order, it so happened that Keśava Bhāratī, a sannyāsī of the Māyāvādī school and resident of Katwa (in Bengal), visited Navadvīpa and was invited to dine with the Lord. When Keśava Bhāratī came to His house, the Lord asked him to award Him the sannyāsa order of life. This was a matter of formality. The sannyāsa order is to be accepted from another sannyāsī. Although the Lord was independent in all respects, still, to keep up the formalities of the śāstras, He accepted the sannyāsa order from Keśava Bhāratī, although Keśava Bhāratī was not in the Vaiṣṇava-sampradāya (school).
(Srimad Bhagavatam------introduction).

The essence of everything is the Supreme Lord: He is called the sāram. And those who sing and talk about Him are called the sāraṅgas, or the pure devotees. The pure devotees are always hankering after the lotus feet of the Lord. The lotus has a kind of honey which is transcendentally relished by the devotees. They are like the bees who are always after the honey. Śrīla Rūpa Gosvāmī, the great devotee ācārya of the Gauḍīya-Vaiṣṇava-sampradāya, has sung a song about this lotus honey, comparing himself to the bee: "O my Lord Kṛṣṇa, I beg to offer my prayers unto You. My mind is like the bee, and it is after some honey. Kindly, therefore, give my bee-mind a place at Your lotus feet, which are the resources for all transcendental honey.
(Srimad Bhagavatam-------1:11:26------purport).

Every woman is expected to be as good and chaste as Devahūti or Bhavānī. Today in Hindu society, unmarried girls are still taught to worship Lord Śiva with the idea that they may get husbands like him. Lord Śiva is the ideal husband, not in the sense of riches or sense gratification, but because he is the greatest of all devotees. Vaiṣṇavānāṁ yathā śambhuḥ: Śambhu, or Lord Śiva, is the ideal Vaiṣṇava. He constantly meditates upon Lord Rāma and chants Hare Rāma, Hare Rāma, Rāma Rāma, Hare Hare. Lord Śiva has a Vaiṣṇava sampradāya, which is called the Viṣṇu Svāmī-sampradāya.
(Srimad Bhagavatam-------2:23:1------purport).

Svādhyāyaḥ means "reading the authorized Vedic scriptures." Even if one is not Kṛṣṇa conscious and is practicing the yoga system, he must read standard Vedic literatures in order to understand. Performance of yoga alone is not sufficient. Narottama dāsa Ṭhākura, a great devotee and ācārya in the Gauḍīya Vaiṣṇava-sampradāya, says that all spiritual activities should be understood from three sources, namely saintly persons, standard scriptures and the spiritual master. These three guides are very important for progress in spiritual life.
(Srimad Bhagavatam-------3:28:4------purport).

To raise oneself from hellish life to the highest position of spiritual understanding is to transform this lust into love of Kṛṣṇa. Śrī Narottama dāsa Ṭhākura, a great ācārya of the Vaiṣṇava sampradāya, said, kāma kṛṣṇa-karmārpaṇe: due to our lust, we want many things for our sense gratification, but the same lust can be transformed in a purified way so that we want everything for the satisfaction of the Supreme Personality of Godhead.
(Srimad Bhagavatam-------3:31:29------purport).

People go to a sanctified place to free themselves from all sinful reactions. In other words, those who are devoted to the lotus feet of the Supreme Personality of Godhead, Kṛṣṇa, automatically become sanctified. The Lord's lotus feet are called tīrtha-pāda because under their protection there are hundreds and thousands of saintly persons who sanctify the sacred places of pilgrimage. Śrīla Narottama dāsa Ṭhākura, a great ācārya of the Gauḍīya Vaiṣṇava-sampradāya, advises us not to travel to different places of pilgrimage. Undoubtedly it is troublesome to go from one place to another, but one who is intelligent can take shelter of the lotus feet of Govinda and thereby be automatically sanctified as the result of his pilgrimage.
(Srimad Bhagavatam-------4:6:25------purport).

The four Kumāras are paramparā spiritual masters of the Vaiṣṇava sampradāya. Out of the four sampradāyas, namely Brahma-sampradāya, Śrī-sampradāya, Kumāra-sampradāya and Rudra-sampradāya, the disciplic succession of spiritual master to disciple known as the Kumāra-sampradāya is coming down from the four Kumāras.
(Srimad Bhagavatam-------4:22:4------purport).

Lord Śiva is known as the greatest devotee of the Supreme Personality of Godhead. He is known as the best of all types of Vaiṣṇavas (vaiṣṇavānāṁ yathā śambhuḥ). Consequently, Lord Śiva has a Vaiṣṇava sampradāya, the disciplic succession known as the Rudra-sampradāya. Just as there is a Brahma-sampradāya coming directly from Lord Brahmā, the Rudra-sampradāya comes directly from Lord Śiva. Lord Śiva is one of the twelve great personalities, as stated in Śrīmad-Bhāgavatam (6.3.20)
(Srimad Bhagavatam-------4:24:18------purport).

The Lord enters within the heart of the living entity and within the atom; therefore both the living entity and the Lord are called purañjana. One purañjana, the living entity, is subordinate to the supreme purañjana; therefore the duty of the subordinate purañjana is to satisfy the supreme purañjana. That is devotional service. Lord Rudra, or Lord Śiva, is the original ācārya of the Vaiṣṇava sampradāya called the Rudra-sampradāya. Rudra-gītena indicates that under the disciplic succession of Lord Rudra, the Pracetās achieved spiritual success.
(Srimad Bhagavatam-------4:30:3------purport).

Some so-called Vaiṣṇavas say that the renounced order of life was not accepted in the Vaiṣṇava sampradāya, or disciplic succession, until Lord Caitanya. This is not a very intelligent proposition. Śrī Caitanya Mahāprabhu took the sannyāsa order from Śrīpāda Keśava Bhāratī, who belonged to the Śaṅkara sect, which approves of only ten names for sannyāsīs. Long before the advent of Śrīpāda Śaṅkarācārya, however, the sannyāsa order existed in the Vaiṣṇava line of Viṣṇu Svāmī. In the Viṣṇu Svāmī Vaiṣṇava sampradāya, there are ten different kinds of sannyāsa names and 108 different names for sannyāsīs who accept the tri-daṇḍa, the triple staff of sannyāsa. This is approved by the Vedic rules. Therefore Vaiṣṇava sannyāsa was existent even before the appearance of Śaṅkarācārya, although those who know nothing about Vaiṣṇava sannyāsa unnecessarily declare that there is no sannyāsa in the Vaiṣṇava sampradāya.
(Sri Caitanya Caritamrta------1:3:34------purport).

Lord Caitanya could have performed His missionary activities as a householder, but He found householder life an obstruction to His mission. Therefore He decided to accept the renounced order, sannyāsa. Since His acceptance of sannyāsa was also designed to attract public attention, Lord Caitanya, not wishing to disturb the social convention, took the renounced order of life from a sannyāsī in the disciplic succession of Śaṅkarācārya, although sannyāsa was also sanctioned in the Vaiṣṇava sampradāya.
(Sri Caitanya Caritamrta------1:3:34------purport).

In the Laghu-bhāgavatāmṛta Śrīla Rūpa Gosvāmī has explained Kṛṣṇa's being both Kṣīrodakaśāyī Viṣṇu and Nārāyaṇa in the spiritual sky and expanding in the quadruple forms known as Vāsudeva, Saṅkarṣaṇa, Pradyumna and Aniruddha. He has refuted the idea that Kṛṣṇa is an incarnation of Nārāyaṇa. Some devotees think that Nārāyaṇa is the original Personality of Godhead and that Kṛṣṇa is an incarnation. Even Śaṅkarācārya, in his commentary on the Bhagavad-gītā, has accepted Nārāyaṇa as the transcendental Personality of Godhead who appeared as Kṛṣṇa, the son of Devakī and Vasudeva. Therefore this matter may be difficult to understand. But the Gauḍīya Vaiṣṇava-sampradāya, headed by Rūpa Gosvāmī, has established the principle of the Bhagavad-gītā that everything emanates from Kṛṣṇa, who says in the Bhagavad-gītā, ahaṁ sarvasya prabhavaḥ: "I am the original source of everything." "Everything" includes Nārāyaṇa. Therefore Rūpa Gosvāmī, in his Laghu-bhāgavatāmṛta, has established that Kṛṣṇa, not Nārāyaṇa, is the original Personality of Godhead.
(Sri Caitanya Caritamrta------1:5:132------purport).

Śrī Mādhavendra Purī is one of the ācāryas in the disciplic succession from Madhvācārya. Mādhavendra Purī had two principal disciples, Īśvara Purī and Śrī Advaita Prabhu. Therefore the Gauḍīya Vaiṣṇava-sampradāya is a disciplic succession from Madhvācārya. This fact has been accepted in the authorized books known as Gaura-gaṇoddeśa-dīpikā and Prameya-ratnāvalī, as well as by Gopāla Guru Gosvāmī.
(Sri Caitanya Caritamrta------1:6:40------purport).

Vallabha Bhaṭṭa is the head of the Vaiṣṇava sampradāya known as the Vallabhācārya-sampradāya in western India. There is a long story about Vallabha Ācārya narrated in the Caitanya-caritāmṛta, specifically in the Seventh Chapter of the Antya-līlā and the Nineteenth Chapter of the Madhya-līlā. Lord Caitanya Mahāprabhu visited the house of Vallabha Ācārya on the other side of Prayāga, in a place known as Āḍāila-grāma. Later, Vallabha Bhaṭṭa saw Caitanya Mahāprabhu at Jagannātha Purī to explain his commentary on Śrīmad-Bhāgavatam.
(Sri Caitanya Caritamrta------2:1:263------purport).

The most intimate devotee of Śrī Caitanya Mahāprabhu, namely Gadādhara Paṇḍita, accepted tridaṇḍa-sannyāsa and also accepted Mādhava Upādhyāya as his tridaṇḍi-sannyāsī disciple. It is said that from this Mādhavācārya the sampradāya known in western India as the Vallabhācārya sampradāya has begun. Śrīla Gopāla Bhaṭṭa Gosvāmī, who is known as a smṛty-ācārya in the Gauḍīya-Vaiṣṇava-sampradāya, later accepted the tridaṇḍa-sannyāsa order from Tridaṇḍipāda Prabodhānanda Sarasvatī.
(Sri Caitanya Caritamrta------2:3:6------purport).

Sanātana Gosvāmī considered himself fallen, for in the association of such men, he also fell victim to material enjoyment. Having passed his life in that way, he considered that he had wasted his valuable time. This statement about how one can become fallen in this material world is made by the greatest authority in the Gauḍīya Vaiṣṇava-sampradāya. Actually the whole world is presently fallen into material existence.
(Sri Caitanya Caritamrta------2:20:99------purport).

Śrīla Advaita Ācārya sets the standard for ācāryas in the Vaiṣṇava sampradāya. An ācārya must always be eager to deliver the fallen souls. A person who establishes a temple or maṭha to take advantage of people's sentiments by using for his livelihood what people contribute for the worship of the Deity cannot be called a gosvāmī or ācārya. One who knows the conclusion of the śāstras, follows in the footsteps of his predecessors and endeavors to preach the bhakti cult all over the world is to be considered an ācārya.
(Sri Caitanya Caritamrta------3:3:223------purport).

This is confirmed in Śrīmad-Bhāgavatam when Nārada speaks of the different symptoms characterizing the four divisions of social life. Nārada therein summarizes that brāhmaṇas, kṣatriyas, vaiśyas and śūdras should be selected by their individual qualifications. In his commentary, Śrīdhara Svāmī has noted that birth in a family of brāhmaṇas does not necessarily mean that one is a brāhmaṇa. One must be qualified with the symptoms of a brāhmaṇa, as the symptoms are described in the śāstras. In the disciplic succession of the Gauḍīya Vaiṣṇava sampradāya, there are two great ācāryas (Ṭhākura Narottama and Śyāmānanda Gosvāmī) who were not born in brāhmaṇa families but were accepted as spiritual masters by many brāhmaṇas of fame, including Gaṅgānārāyaṇa, Rāmakṛṣṇa, etc.
(Teachings of Lord Caitanya).

In the Middle Ages, after the disappearance of Lord Caitanya's great associate Lord Nityānanda, a class of priestly persons claimed to be the descendants of Nityānanda, calling themselves the gosvāmī caste. They further claimed that the practice and spreading of devotional service belonged only to their particular class, which was known as Nityānanda-vaṁśa. In this way, they exercised their artificial power for some time, until Śrīla Bhaktisiddhānta Sarasvatī Ṭhākura, the powerful ācārya of the Gauḍīya Vaiṣṇava sampradāya, completely smashed their idea. There was a great hard struggle for some time, but it has turned out successfully, and it is now correctly and practically established that devotional service is not restricted to a particular class of men.
(Nectar of devotion).

There is a spiritual sky. There is another nature, which is beyond manifestation and nonmanifestation. But how will you know that there is a sky where the planets and inhabitants are eternal? All this knowledge is there, but how will you make experiments? It is not possible. Therefore you have to take the assistance of the Vedas. This is called Vedic knowledge. In our Kṛṣṇa consciousness movement we are accepting knowledge from the highest authority, Kṛṣṇa. Kṛṣṇa is accepted as the highest authority by all classes of men. I am speaking first of the two classes of transcendentalists. One class of transcendentalists is called impersonalistic, Māyāvādī. They are generally known as Vedāntists, led by Śaṅkarācārya. And there is another class of transcendentalists, called Vaiṣṇavas, like Rāmānujācārya, Madhvācārya, Viṣṇu Svāmī. Both the Śaṅkara-sampradāya and the Vaiṣṇava-sampradāya have accepted Kṛṣṇa as the Supreme Personality of Godhead.
(Sri Isopanishad).