Text 13

 mahatmanas tu mam partha
daivim prakritim asritah
bhajanty ananya-manaso
jnatva bhutadim avyayam

Translation

O son of Pritha, those who are not deluded, the great souls, are under the protection of the divine nature. They are fully engaged in devotional service because they know Me as the Supreme Personality of Godhead, original and inexhaustible.

 Commentary by Srila Prabhupada 

In this verse the description of the mahatma is clearly given. The first sign of the mahatma is that he is already situated in the divine nature. He is not under the control of material nature. And how is this effected? That is explained in the Seventh Chapter: one who surrenders unto the Supreme Personality of Godhead, Sri Krishna, at once becomes freed from the control of material nature. That is the qualification. One can become free from the control of material nature as soon as he surrenders his soul to the Supreme Personality of Godhead. That is the preliminary formula. Being marginal potency, as soon as the living entity is freed from the control of material nature, he is put under the guidance of the spiritual nature. The guidance of the spiritual nature is called daivi prakriti, divine nature. So when one is promoted in that way—by surrendering to the Supreme Personality of Godhead—one attains to the stage of great soul, mahatma. 

The mahatma does not divert his attention to anything outside Krishna, because he knows perfectly well that Krishna is the original Supreme Person, the cause of all causes. There is no doubt about it. Such a mahatma, or great soul, develops through association with other mahatmas, pure devotees. Pure devotees are not even attracted by Krishna’s other features, such as the four-armed Maha-Vishnu. They are simply attracted by the two-armed form of Krishna. They are not attracted to other features of Krishna, nor are they concerned with any form of a demigod or of a human being. They meditate only upon Krishna in Krishna consciousness. They are always engaged in the unswerving service of the Lord in Krishna consciousness.

Commentary by Sri Visvanatha Cakravarti Thakur

But those men who attain greatness by unpredictable mercy of my devotees attain the nature of the devas (daivim prakrtim) (rather than asuras), and worship me in my human-like form. Their minds do not dwell on such things as desires for jnana or karma (ananya manasah). By knowledge of my powers (maya tatam idam sarvam), they know that I am the cause of all the unlimited bodies starting with Brahma (bhutadim). They know that I am indestructible (avayayam), since I have a body of sac cid ananda. For understanding that I am worthy of worship, they should have at least this much knowledge of me. Knowing this (jnatva), they worship me. It should be understood that this bhakti, which is not dependent on jnana and karma which take tvam or the self as God, which is exclusively centered on the Lord, is the best of all, the king of knowledge, the king of secrets.