There are two classes of sannyāsīs, or persons in the renounced order of life. The Māyāvādī sannyāsīs are engaged in the study of Sāṅkhya philosophy, whereas the Vaiṣṇava sannyāsīsare engaged in the study of Bhāgavatam philosophy, which affords the proper commentary on the Vedānta-sūtras. The Māyāvādī sannyāsīs also study the Vedānta-sūtras, but use their own commentary, called Śārīraka-bhāṣya, written by Śaṅkarācārya. The students of the Bhāgavata school are engaged in the devotional service of the Lord, according to pāñcarātrikī regulations, and therefore the Vaiṣṇava sannyāsīs have multiple engagements in the transcendental service of the Lord. The Vaiṣṇava sannyāsīs have nothing to do with material activities, and yet they perform various activities in their devotional service to the Lord. But the Māyāvādī sannyāsīs, engaged in the studies of Sāṅkhya and Vedānta and speculation, cannot relish the transcendental service of the Lord. Because their studies become very tedious, they sometimes become tired of Brahman speculation, and thus they take shelter of the Bhāgavatam without proper understanding. Consequently their study of the Śrīmad-Bhāgavatam becomes troublesome. Dry speculations and impersonal interpretations by artificial means are all useless for the Māyāvādī sannyāsīs. The Vaiṣṇava sannyāsīs, who are engaged in devotional service, are happy in the discharge of their transcendental duties, and they have the guarantee of ultimate entrance into the kingdom of God. The Māyāvādī sannyāsīs sometimes fall down from the path of self-realization and again enter into material activities of a philanthropic and altruistic nature, which are nothing but material engagements. Therefore, the conclusion is that those who are engaged in Kṛṣṇa conscious activities are better situated than the sannyāsīs engaged in simple speculation about what is Brahman and what is not Brahman, although they too come to Kṛṣṇa consciousness, after many births.
(Bhagavad-Gita----5:6----purport).

The transcendental attitude of the devotee in the performance of activities is actually that of renunciation, and this is called sannyāsa. As stated in the first verse of the Sixth Chapter of Bhagavad-gītā, one who acts as a matter of duty because he has been ordered to do so by the Supreme Lord, and who does not seek shelter in the fruits of his activities (anāśritaḥ karma-phalam), is a true renouncer. Anyone acting under the direction of the Supreme Lord is actually a sannyāsī and a yogī, and not the man who has simply taken the dress of the sannyāsī, or a pseudo yogī.
(Bhagavad-Gita----10:3----purport).

The sannyāsīs beg from door to door, not for money but for missionary purposes. The system is that they go from door to door to awaken the householders from the slumber of ignorance. Because the householders are engaged in family affairs and have forgotten their actual purpose in life—awakening their Kṛṣṇa consciousness—it is the business of the sannyāsīs to go as beggars to the householders and encourage them to be Kṛṣṇa conscious.
(Bhagavad-Gita----10:4-5----purport).

In the varṇāśrama institution the sannyāsī, or the person in the renounced order of life, is considered to be the head or the spiritual master of all the social statuses and orders. A brāhmaṇa is considered to be the spiritual master of the three other sections of a society, namely, the kṣatriyas, the vaiśyas and the śūdras, but a sannyāsī, who is on the top of the institution, is considered to be the spiritual master of the brāhmaṇas also.
(Bhagavad-Gita----16:1-3----purport).

For a sannyāsī, the first qualification should be fearlessness. Because a sannyāsī has to be alone without any support or guarantee of support, he has simply to depend on the mercy of the Supreme Personality of Godhead. If one thinks, "After I leave my connections, who will protect me?" he should not accept the renounced order of life. One must be fully convinced that Kṛṣṇa or the Supreme Personality of Godhead in His localized aspect as Paramātmā is always within, that He is seeing everything and He always knows what one intends to do. One must thus have firm conviction that Kṛṣṇa as Paramātmā will take care of a soul surrendered to Him. "I shall never be alone," one should think. "Even if I live in the darkest regions of a forest I shall be accompanied by Kṛṣṇa, and He will give me all protection." That conviction is called abhayam, fearlessness. This state of mind is necessary for a person in the renounced order of life.
(Bhagavad-Gita----16:1-3----purport).

There are so many rules and regulations to be followed in the renounced order of life. Most important of all, a sannyāsī is strictly forbidden to have any intimate relationship with a woman. He is even forbidden to talk with a woman in a secluded place. Lord Caitanya was an ideal sannyāsī, and when He was at Purī His feminine devotees could not even come near to offer their respects. They were advised to bow down from a distant place. This is not a sign of hatred for women as a class, but it is a stricture imposed on the sannyāsīnot to have close connections with women.
(Bhagavad-Gita----16:1-3----purport).

For a sannyāsī, intimate relations with women and possession of wealth for sense gratification are strictly forbidden. The ideal sannyāsī was Lord Caitanya Himself, and we can learn from His life that He was very strict in regards to women. Although He is considered to be the most liberal incarnation of Godhead, accepting the most fallen conditioned souls, He strictly followed the rules and regulations of the sannyāsa order of life in connection with association with woman. One of His personal associates, namely Choṭa Haridāsa, was associated with Lord Caitanya along with His other confidential personal associates, but somehow or other this Choṭa Haridāsa looked lustily on a young woman, and Lord Caitanya was so strict that He at once rejected him from the society of His personal associates. Lord Caitanya said, "For a sannyāsī or anyone who is aspiring to get out of the clutches of material nature and trying to elevate himself to the spiritual nature and go back home, back to Godhead, for him, looking toward material possessions and women for sense gratification—not even enjoying them, but just looking toward them with such a propensity—is so condemned that he had better commit suicide before experiencing such illicit desires." So these are the processes for purification.
(Bhagavad-Gita----16:1-3----purport).

Sannyāsī life is meant for distributing knowledge to the householders and others who have forgotten their real life of spiritual advancement. A sannyāsī is supposed to beg from door to door for his livelihood, but this does not mean that he is a beggar.
(Bhagavad-Gita----16:1-3----purport).

Humility is also one of the qualifications of a transcendentally situated person, and out of sheer humility the sannyāsī goes from door to door, not exactly for the purpose of begging, but to see the householders and awaken them to Kṛṣṇa consciousness. This is the duty of a sannyāsī. If he is actually advanced and so ordered by his spiritual master, he should preach Kṛṣṇa consciousness with logic and understanding, and if one is not so advanced he should not accept the renounced order of life. But even if one has accepted the renounced order of life without sufficient knowledge, he should engage himself fully in hearing from a bona fide spiritual master to cultivate knowledge.
(Bhagavad-Gita----16:1-3----purport).

There are many purificatory processes for advancing a human being to spiritual life. The marriage ceremony, for example, is considered to be one of these sacrifices. It is called vivāha-yajña. Should a sannyāsī, who is in the renounced order of life and who has given up his family relations, encourage the marriage ceremony? The Lord says here that any sacrifice which is meant for human welfare should never be given up. Vivāha-yajña, the marriage ceremony, is meant to regulate the human mind so that it may become peaceful for spiritual advancement. For most men, this vivāha-yajña should be encouraged even by persons in the renounced order of life.
(Bhagavad-Gita----18:5----purport).

It is said that a person in the renounced order of life should not cook for himself. Cooking for oneself is prohibited, but cooking for the Supreme Lord is not prohibited. Similarly, a sannyāsī may perform a marriage ceremony to help his disciple in the advancement of Kṛṣṇa consciousness. If one renounces such activities, it is to be understood that he is acting in the mode of darkness.
(Bhagavad-Gita----18:7----purport).

In the sannyāsa order also there are four stages of upliftment toward perfection. These stages are called kuṭīcaka, bahūdaka, parivrājakācārya, and paramahaṁsa. The paramahaṁsa stage of life is the highest stage of perfection. This order of life is respected by all others.
(Srimad Bhagavatam----1:3:13----purport).

It is the duty of a mendicant (parivrājakācārya) to experience all varieties of God's creation by traveling alone through all forests, hills, towns, villages, etc., to gain faith in God and strength of mind as well as to enlighten the inhabitants with the message of God. A sannyāsī is duty-bound to take all these risks without fear, and the most typical sannyāsīof the present age is Lord Caitanya, who traveled in the same manner through the central Indian jungles, enlightening even the tigers, bears, snakes, deer, elephants and many other jungle animals.
(Srimad Bhagavatam----1:3:16----purport).

In this age of Kali, sannyāsa is forbidden for ordinary men. One who changes his dress to make propaganda is a different man from the original ideal sannyāsī. One should, however, take the vow to stop social intercourse completely and devote life exclusively to the service of the Lord. The change of dress is only a formality. Lord Caitanya did not accept the name of asannyāsī, and in this age of Kali the so-called sannyāsīs should not change their former names, following in the footsteps of Lord Caitanya. In this age, devotional service of hearing and repeating the holy glories of the Lord is strongly recommended, and one who takes the vow of renunciation of family life need not imitate the parivrājakācārya like Nārada or Lord Caitanya, but may sit down at some holy place and devote his whole time and energy to hear and repeatedly chant the holy scriptures left by the great ācāryas like the six Gosvāmīs of Vṛndāvana.
(Srimad Bhagavatam----1:6:14----purport).

The sannyāsīs accept a rod as the sign of the renounced order of life. There are two types of sannyāsīs. Those who follow the Māyāvādī philosophy, headed by Śrīpāda Śaṅkarācārya, accept only one rod (eka-daṇḍa), but those who follow the Vaiṣṇavite philosophy accept three combined rods (tri-daṇḍa). The Māyāvādī sannyāsīs are ekadaṇḍi-svāmīs, whereas the Vaiṣṇava sannyāsīs are known as tridaṇḍi-svāmīs, or more distinctly, tridaṇḍi-gosvāmīs, in order to be distinguished from the Māyāvādī philosophers. The ekadaṇḍi-svāmīs are mostly fond of the Himalayas, but the Vaiṣṇava sannyāsīs are fond of Vṛndāvana and Purī. The Vaiṣṇava sannyāsīs are narottamas, whereas the Māyāvādī sannyāsīs are dhīras.
(Srimad Bhagavatam----1:13:30----purport).

The brāhmaṇas are the religious preceptors for all other castes, and the sannyāsīs are the spiritual masters for all the castes and orders of society. So also are the king and the public leaders who are responsible for the material welfare of all people. The progressive religionists and those who are responsible human beings or those who do not want to spoil their valuable human lives should refrain from all the principles of irreligiosity, especially illicit connection with women. If a brāhmaṇa is not truthful, all his claims as a brāhmaṇa at once become null and void. If a sannyāsī is illicitly connected with women, all his claims as a sannyāsī at once become false. Similarly, if the king and the public leader are unnecessarily proud or habituated to drinking and smoking, certainly they become disqualified to discharge public welfare activities. Truthfulness is the basic principle for all religions. The four leaders of the human society, namely the sannyāsīs, the brāhmaṇa, the king and the public leader, must be tested crucially by their character and qualification. Before one can be accepted as a spiritual or material master of society, he must be tested by the above-mentioned criteria of character. Such public leaders may be less qualified in academic qualifications, but it is necessary primarily that they be free from the contamination of the four disqualifications, namely gambling, drinking, prostitution and animal slaughter.
(Srimad Bhagavatam----1:17:41----purport).

A sannyāsī should always live alone, without company, and he must be fearless. He should never be afraid of living alone, although he is never alone. The Lord is residing in everyone's heart, and unless one is purified by the prescribed process, one will feel that he is alone. But a man in the renounced order of life must be purified by the process; thus he will feel the presence of the Lord everywhere and will have nothing to fear (such as being without any company). Everyone can become a fearless and honest person if his very existence is purified by discharging the prescribed duty for each and every order of life. One can become fixed in one's prescribed duty by faithful aural reception of Vedic instructions and assimilation of the essence of Vedic knowledge by devotional service to the Lord.
(Srimad Bhagavatam----2:2:5----purport).