By Patita Pavana das Adhikary
Who Is A Sadhu? From: Shri Chanakya Niti Shastra
pralaye bhin’namarya-da- bhavanti kila sa-gara-h sa-gara- bhedamicchanti pralaye ‘pi na sa-dhavah
Translation: At the time of pralaya the oceans exceed their limits. Yet a saintly man always remains steady, even under extreme circumstances. (Shri Chanakya Niti Shastra 3.6)
Commentary: Pralaya means “universal destruction”, but here the great Chanakya Pandit expects a proper gentleman, a sadhu, to remain composed and controlled even then. Chanakya’s instruction may be compared to the lesson of Sage Jamadagni to his son Lord Parushurama: “O great hero, my dear son Parashurama, you have unnecessarily killed the king, who is supposed to be the embodiment of all the demigods. Thus you have committed a sin. We are all brahmanas and have become worshipable for the people in general because of our quality of forgiveness. It is because of this quality that Lord Brahma, the supreme spiritual master of this universe, has achieved his post.” (Shrimad Bhagavatam 9.15.38-9)
As explained by Lord Shri Krishna to Arjuna, a man loses control when he becomes a slave of his senses, like a chariot pulled by many horses out of control. The six senses—including the tongue, ears, eyes, nose, touch and mind—are controlled by the process of yoga as described in Bhagavad Gita (2.58): “One who is able to withdraw his senses from the objects of the senses as a tortoise withdraws his limbs is firmly fixed in perfect consciousness.” Still, Arjuna counters with the objection, “The system of yoga that You have summarized appears impractical and unendurable to me, for the mind is restless and unsteady.” (BG 6.33)
Arjuna was the son of Indra—he was a powerful warrior and a personal friend of Lord Krishna. If mighty Arjuna considered the system of ashtanga-yoga, the “eightfold path”, as impractical due to the unsteady nature of the mind, then what to speak of us who have been born 5100 years into the Age of Kali? For the devotee of the Lord, like Arjuna, these six senses or shad-indriyas are automatically controlled by engaging each one in the service of the Lord Shri Krishna. How is this achieved?
In the seventh canto of Shrimad Bhagvatam, Shrila Prabhupada describes the recommended processes of devotional service, bhakti-yoga, that will instill perfection to the heart of the sincere devotee. “Maharaja Ambarish always engaged his mind in meditating upon the lotus feet of Krishna, his words in describing the glories of the Lord, his hands in cleansing the Lord’s temple, and his ears in hearing the words spoken by Krishna or about Krishna. He engaged his eyes in seeing the Deity of Krishna, Krishna’s temples, and Krishna’s places like Mathura and Vrindavana, he engaged his sense of touch in touching the bodies of the Lord’s devotees, he engaged his sense of smell in smelling the fragrance of tulsi offerdd to the Lord, and he engaged his tongue in tasting the Lord’s prasad. He engaged his legs in walking to the holy places and temples of the Lord, his head in bowing down before the Lord, and all his desires in serving the Lord, twenty-four hours a day. Indeed Maharaja Ambarish never desired anything for his own sense gratification. He engaged all his senses in devotional; service, in various engagements related to the Lord. This is the way to increase attachment for the Lord and be completely free from all material desires.”
In Kali Yuga, steadiness of heart and mind is perfected through the holy names of the Lord. Therefore, following in the footsteps of his Guru Maharaja and Lord Shri Chaitanya Mahaprabhu, Shrila Prabhupada was always heard, even in his sleep, to be chanting:
Hare Krishna Hare Krishna Krishna Krishna Hare Hare Hare Rama Hare Rama Rama Rama Hare Hare.

titiksavah karunikah
suhrdah sarva-dehinam
ajata-satravah santah
sadhavah sadhu-bhusanah
Just to list a few characteristics of a sadhu yet again: tolerant, merciful, friendly to others. without enemies, peaceful and he abides by the scriptures — these are characteristics of a sadhu. Yet as you point out — the fact that he does not flinch of fail under a test is certainly an important symptom.
From Visvanatha’s commentary for Bhagavad-gita 2.41:
This is a bit of elaboration on the subject that could be helpful and can produce some further incites. Prabhupada himself molded his life on this principle of vayavasatmika budhih verse and the Srila Visvanatha Carkavarti’s comments on it, so we may as well know about it, even if our dedication is not as strong, for us certainly perfection is in following Prabhupada and perfection of a spiritual master or a leader in ISKCON is in the same principle. This is the basic, guru-nistha, mood in which we can chant and is ultimately only possible if we are humble, or humiliated, which helps as well and should be taken as a blessing.