The statements of Thakura Bhaktivinode are as good as scriptures because he is liberated person. Generally the spiritual master comes from the group of such eternal associates of the Lord; but anyone who follows the principles of such ever liberated persons is as good as one in the above mentioned group. The gurus from nature’s study are accepted as such on the principle that an elevated person in Krishna Consciousness does not accept anyone as disciple, but he accepts everyone as expansion of his guru. That is very high position, called Maha-bhagavata. Just like Radharani, sometimes thinks a subordinate of hers as her teacher, to understand devotion of Krishna. A person who is liberated acharya and guru cannot commit any mistake, but there are persons who are less qualified or not liberated, but still can act as guru and acharya by strictly following the disciplic succession. It is the injunction of the sastras that anyone who sees the Deity in the Temple as made of wood or stone, or considers the acaryas and gurus as ordinary common men, and discriminates Vaisnavas or devotees as belonging to a certain group or caste, are called hellish. (Letter to Janardana—New York26 April, 1968)
“Mukunda dāsa externally appears to be a royal physician engaged in governmental service, but internally he has a deep love for Kṛṣṇa. Who can understand his love?
Unless Śrī Kṛṣṇa Caitanya Mahāprabhu discloses the fact, no one can understand who is actually a great devotee of the Lord engaged in His service. It is therefore said in Caitanya-caritāmṛta (Madhya 23.39), tāṅra vākya, kriyā, mudrā vijñeha nā bujhaya: even the most perfect and learned scholar cannot understand a Vaiṣṇava’s activities. A Vaiṣṇava may be engaged in governmental service or in a professional business so that externally one cannot understand his position. Internally, however, he may be a nitya-siddha Vaiṣṇava-that is, an eternally liberated Vaiṣṇava. Externally Mukunda dāsa was a royal physician, but internally he was the most liberated paramahaṁsa devotee. Śrī Caitanya Mahāprabhu knew this very well, but ordinary men could not understand it, for the activities and plans of a Vaiṣṇava cannot be understood by ordinary men. However, Śrī Caitanya Mahāprabhu and His representative understand everything about a devotee, even though the devotee may externally pretend to be an ordinary householder and professional businessman. (cc/madhya/15/120)