CC Madhya 15.120
antare kṛṣṇa-prema iṅhāra jānibeka kebā
“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 the 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.