Lord Brahma, the creator, one day visits Sri Krishna’s Palace in Dwarka. There are gatekeepers there who stopped Brahma and asked Sri Krishna whether he should enter or not. Sri Krishna told the gatekeepers Which Brahma came? The gatekeepers repeated the words to Brahma outside the palace. Lord Brahma was shocked !! I am the creator of the Universe, how dare Sri Krishna tell me which Brahma !! I am the Prajapati. He told the gatekeepers to tell Sri Krishna that the 4-headed Brahma came.
When they told that to Sri Krishna, he instructed them to tell Lord Brahma to enter. After entering, awe-struck, he replied to Sri Krishna - Why did you say that which Brahma came? I am the only one !!
Then, Sri Krishna said- Let’s see. Then the magic happens. Lord Brahma saw other Brahma’s are coming to the palace riding the swan. The number is so gigantic that he can’t count how many Brahma’s there are. Some of them had 10 heads, some had 100, some had 1000 heads, depending on the size of their universe. Compared to them, our Brahma’s Universe is very very small.
Then, Sri Krishna told our Brahma that you are not the only Brahma. There are countless Universes each has its own Brahma. Then, finally, the Arrogance of our Brahma broke. He sincerely apologized to Sri Krishna.
Thats how Brahma realized that our Universe is not the only one. It’s just one of the countless Universes.