One who has unflinching faith in Kṛṣṇa, one who is cent percent engaged to render service to Kṛṣṇa, he is called sādhu. Sādhu does not mean a kind of dress or kind of beard. No. Sādhu means a devotee, perfect devotee of Kṛṣṇa. That is . . . he is sādhu.
Therefore it is recommended, sādhu-saṅga. We have to associate with sādhu, means who have completely dedicated life for Kṛṣṇa's service. That is the injunction in the Bhagavad-gītā. Man-manā bhava mad-bhakto mad-yājī māṁ namaskuru (BG 18.65). This process is very simple. Kṛṣṇa advises, Himself, how to become a sādhu, how to become a saintly person. That is also. Only follow four principles: man-manā bhava mad-bhakto. You simply think of Kṛṣṇa, man-manā. You just become devotee of Kṛṣṇa, man-manā bhava mad-bhak . . . mad-yājī—you simply worship Kṛṣṇa. Man-manā bhava mad-bhak . . . māṁ namaskuru—"You offer your obeisances unto Me." These four principles.
Think of Kṛṣṇa. That thinking of Kṛṣṇa we have introduced. We have not introduced; it is introduced from Vedic literature—Hare Kṛṣṇa, Hare Kṛṣṇa, Kṛṣṇa Kṛṣṇa, Hare Hare/ Hare Rāma, Hare Rāma, Rāma Rāma, Hare Hare. If you chant these sixteen words, it is not very difficult. Anyone; there is no secrecy. There is no charge for it. We don't say that, "I shall give you some secret mantra. You give me some money." No. We don't say. We openly chant this Hare Kṛṣṇa mantra. Anyone can chant also. But see the effect of chanting this mantra. That is up to you. If you begin chanting, you'll feel effect very soon.