Though Lord Krishna grew as a cowherd boy along with the others, He revealed His supremacy whenever the situation demanded it. The picture of Lord Krishna — in the company of cowherds, grazing the cows, enjoying the serene surroundings, partaking the simple food of the Vraja folk, playing the charming flute, while also displaying divine grace as in the killing of Aghasura — became a matter of envy for Brahma. The Lord, who is the Supreme Being to whom all sacrifices are offered and who is the enjoyer of all sacrifices, was now enjoying His childhood pastime.
Ignorance feeds one's ego and blinds us to truth and Brahma became a victim to his ego when he attempted to mystify Lord Krishna, said Asuri Sri Madhavachariar in a lecture. He took away the calves and hid them by his divine power. To alleviate the anxiety of the cowherd boys, Lord Krishna went in search of the calves that had disappeared all of a sudden. Brahma used this opportunity to hide the companions of the Lord as well.
The Lord knew the plan of Brahma and to teach him a lesson, He assumed the form of the lost calves and cowherd boys, including their possessions such as the slings, blow horns, flutes, etc. In fact, since the Lord had assumed all these forms, all the activities in Vraja went on as usual, and there was extra glow and endearment in them.
When Brahma returned to Gokula after a year (though it was but a moment according to his reckoning) and released his captives, they mingled with those who were actually a manifestation of the Lord. Brahma was baffled by the likeness and identity of the old and the new group. The Lord chose to clear his confusion and made him realise the extent of His power. Brahma was able to see the distinguishing marks of the Lord, the crown, the conch and the discus, four arms, etc. see the Lord in those forms.
Brahma realises the inscrutable power of the Lord's Maya. It had cast a spell on him. Brahma sings a hymn in praise of the ultimate supremacy of the Lord. He regrets the way he had become susceptible to pride, envy and anger — enemies to the welfare of all beings. He offers obeisance to the Lord and surrenders himself at His feet.