O Arjuna, mercifully have I shown you this Supreme Form by My own power of yoga – this effulgent, infinite, primeval, great Universal Form of Mine, which has not been seen by anyone else before you. (Bhagavad Gita Chapter XI – Verse 47)
How can that Form be seen? I will tell you. First I shall give you the negative side to remove all misconception.
O great hero of the Kurus, not by the study of the sacred Vedas or by sacrifice, not by charity or rituals, nor by severe austerities am I visible in such form in this world of men to anyone other than you. (Bhagavad Gita Chapter XI – Verse 48)
People think that by these practices, by their yoga power they can gain Me. But that is not so, It is My yoga power that reveals the Truth. ‘Whom the Atman chooses to him is the Atman revealed.’ I do not choose these great, self-righteous ascetics who think that since they have done such wonderful things, they can demand from Me. No, not to them do I reveal Myself, but only to My own children. But I will tell you about that later. Now first see My old form again and be quiet and at peace. Then you will be able to understand that great secret.
Be not frightened nor bewildered, having seen this terrific form of Mine; getting rid of your fear and with a gladdened heart, be hold you again this, My former form. (Bhagavad Gita Chapter XI – Verse 49)
Now look at Me. Here I am again, your friend, your charioteer. Be happy and compose yourself. Then I will continue My discourse. An agitated mind cannot absorb what is said. It only hears half and forgets again immediately. Therefore first become calm; then you will be able to benefit from My words. My words are very important; you should never forget them. So pay strict attention. I am going to give you in a few words the whole secret of religion, all that you need know, all that any one need know.