In the Third Canto, 15th Chapter, 43rd verse of Śrīmad-Bhāgavatam there is a statement by the four saintly persons known as Catuḥsana, headed by Sanaka-kumāra. They went to visit the Lord of Vaikuṇṭha-loka in the spiritual sky, and when they bowed down before the Lord, the aroma of the tulasī, mixed with saffron, entered their nostrils and immediately attracted their minds. Although these four saintly persons were always absorbed in the thought of impersonal Brahman, from association with the Lord and from smelling the tulasī leaves, the hairs on their bodies immediately stood up. This shows that even a person who is situated in Brahman realization, if he is put into association with devotees in pure devotional service, will immediately become attracted to the personal feature of the Lord.
There are certain symptoms of great sages who are situated in śānta-rasa devotional service, and these symptoms are exhibited as follows: they concentrate their eyesight on the tip of the nose, and they behave just like an avadhūta. Avadhūta means a highly elevated mystic who does not care for any social, religious or Vedic conventions. Another symptom is that such persons are very careful to step forward when giving speeches. When they speak, they join together the forefinger and thumb. (This is called the jñāna-mudrā position.) They are not against the atheists, nor are they particularly inclined to the devotees. Such persons give stress to liberation and detachment from the materialistic way of life. They are always neutral and have no affection for nor misidentification with anything material. They are always grave, but fully absorbed in thoughts of the Supreme Personality of Godhead. These uncommon features develop in devotees who are situated in śānta-rasa.
Regarding concentration of the eyesight on the tip of the nose, there is a statement in the Bhakti-rasāmṛta-sindhu by a devotee who observed this being performed by a yogī. He remarked, "This great sage is concentrating his eyesight on the tip of his nose, and from this it appears that he has already realized the eternal form of the Lord within himself."
Sometimes a devotee in śānta-rasa yawns, stretches his limbs, instructs on devotional service, offers respectful obeisances unto the form of the Lord, offers nice prayers to the Lord and has a desire to give direct service with his body. These are some of the common symptoms of the devotee who is situated in neutrality. One devotee, after observing the yawning of another devotee, addressed him thus: "My dear mystic, I think that within your heart there is some ecstatic devotional love which is causing you to yawn." It is sometimes found that a devotee in the śānta-rasa falls down on the ground, his hairs stand up on his body, and he trembles all over. In this way, different symptoms of ecstatic trance are exhibited automatically by such devotees.