The test of a yogī, devotee, or self-realized soul is that he is able to control the senses according to his plan. Most people, however, are servants of the senses and are thus directed by the dictation of the senses. That is the answer to the question as to how the yogī is situated. The senses are compared to venomous serpents. They want to act very loosely and without restriction. The yogī, or the devotee, must be very strong to control the serpents—like a snake charmer. He never allows them to act independently.
(Bhagavad-Gita--2:58---purport).

All rituals, all performances of sacrifices, and everything that is put into the Vedas, including all direction for material activities, are meant for understanding Kṛṣṇa, who is the ultimate goal of life. But because the conditioned souls do not know anything beyond sense gratification, they study the Vedas to that end. But through fruitive activities and sense gratification regulated by the Vedic rituals one is gradually elevated to Kṛṣṇa consciousness. Therefore a realized soul in Kṛṣṇa consciousness should not disturb others in their activities or understanding, but he should act by showing how the results of all work can be dedicated to the service of Kṛṣṇa.
(Bhagavad-Gita--3:26---purport).

By transcendental knowledge one can remain steady in his convictions, but by mere academic knowledge one can be easily deluded and confused by apparent contradictions. It is the realized soul who is actually self-controlled, because he is surrendered to Kṛṣṇa. He is transcendental because he has nothing to do with mundane scholarship. For him mundane scholarship and mental speculation, which may be as good as gold to others, are of no greater value than pebbles or stones.
(Bhagavad-Gita--6:8---purport).

One must be very meek and submissive and try to live peacefully by lending the ear to the speeches of the transcendentally self-realized soul who speaks on the message of Bhāgavata-dharma, or the religion of glorifying the Supreme Lord and His devotees.
(Srimad Bhagavatam-introduction).

Śrīla Śukadeva Gosvāmī is the topmost personality of all the self-realized souls, and he accepted this as the subject of studies from his father, Vyāsadeva.
(Srimad Bhagavatam--1:1:41--purport).

Those who are in the spiritual world are known to be completely self-realized because on the spiritual platform the living entity is not forgetful of his service to the Lord. Therefore in the spiritual world all those who are in the devotional service of the Lord are eternally fixed, for they understand the position of the Supreme Being, as well as their individual constitution. Thus amongst self-realized souls, the Lord is known as the perfectly self-realized soul.
(Srimad Bhagavatam--4:24:33---purport).

This material world is called tamaḥ, dark, and the spiritual world is called light. The Vedas enjoin that everyone should try to get out of the darkness and go to the kingdom of light. Information of that kingdom of light can be attained through the mercy of a self-realized soul. One also has to get rid of all material desires. As soon as one frees himself from material desires and associates with a liberated person, the path back home, back to Godhead, is clear.
(Srimad Bhagavatam---4:31:29).