(Srila Prabhupada in Moscow, 1971)
Prabhupāda: So we have to follow. Mahājano yena gataḥ sa panthāḥ (CC Madhya 17.186). Don't follow rascals and fools. Then it will be useless waste of time. Follow the great ācāryas. Ācāryavān puruṣo veda. One who is ācāryavān, who has accepted ācārya, he knows. Others, all are fools, rascals. Ācāryavān. Ācāryopāsanam.
In the Bhagavad-gītā it is said, amānitvam adambhitvam ahiṁsā kṣāntir ārjavam, ācāryopāsanam (BG 13.8). You have to first of all worship the ācārya. Tad-vijñānārthaṁ sa gurum evābhigacchet (MU 1.2.12). Guru and ācārya, the same thing. So these are the process. Mahājano yena gataḥ.
You cannot manufacture your ways of thinking. What you are? You are most insignificant living entity. And without following the ācāryas, without following the mahājanas, without following the śāstra, how you can teach? But people are doing that. Without being followed by the ācārya, without being followed by the śāstras, they become guru, they become svāmī, they become yogī. It is useless.
(Srila Prabhupada Lecture, Calcutta, September 27, 1974)