When Krsna and Balarama were playing with Their friends, all the boys joined Balarama and told mother Yasoda that Krsna had eaten clay.
On hearing this, mother Yasoda caught hold of Krsna's hand and said, "My dear Krsna, why have You eaten earth in a solitary place? Just see, all Your friends including Balarama are complaining about You."
Being afraid of His mother, Krsna replied, "My dear mother, all these boys, including My elder brother Balarama, are speaking lies against Me. I have never eaten clay. My elder brother Balarama, while playing with Me today, became angry, and therefore He has joined with the other boys to complain against Me. They have all combined together to complain so you will be angry and chastise Me. If you think they are truthful, then you can look within My mouth to see whether I have taken clay or not."
His mother replied, "All right, if You have actually not taken any clay, then just open Your mouth. I shall see."
When the Supreme Personality of Godhead Krsna was so ordered by His mother, He immediately opened His mouth just like an ordinary boy. Then mother Yasoda saw within that mouth the complete opulence of creation. She saw the entire outer space in all directions, mountains, islands, oceans, seas, planets, air, fire, moon and stars. Along with the moon and the stars she also saw the entire elements, water, sky, the extensive ethereal existence along with the total ego and the products of the senses and the controller of the senses, all the demigods, the objects of the senses like sound, smell, etc., and the three qualities of material nature.
She also could perceive that within His mouth were all living entities, eternal time, material nature, spiritual nature, activity, consciousness and different forms of the whole creation. Yasoda could find within the mouth of her child everything necessary for cosmic manifestation. She also saw, within His mouth, herself taking Krsna on her lap and having Him sucking her breast.
Upon seeing all this, she became struck with awe and began to wonder whether she were dreaming or actually seeing something extraordinary. She concluded that she was either dreaming or seeing the play of the illusory energy of the Supreme Personality of Godhead. She thought that she had become mad, mentally deranged, to see all those wonderful things.
Then she thought, "It may be cosmic mystic power attained by my child, and therefore I am perplexed by such visions within His mouth. Let me offer my respectful obeisances unto the Supreme Personality of Godhead under whose energy bodily self and bodily possessions are conceived."
She then said, "Let me offer my respectful obeisances unto Him, under whose illusory energy I am thinking that Nanda Maharaja is my husband and Krsna is my son, that all the properties of Nanda Maharaja belong to me and that all the cowherd men and women are my subjects. All this misconception is due to the illusory energy of the Supreme Lord. So let me pray to Him that He may protect me always."
While mother Yasoda was thinking in this high philosophical way, Lord Krsna again expanded His internal energy just to bewilder her with maternal affection. Immediately mother Yasoda forgot all philosophical speculation and accepted Krsna as her own child. She took Him on her lap and became overwhelmed with maternal affection.
-- Krsna Book (Chapter eight, titled: "Vision of the Universal Form.")