And in my mind as I was floating
Far above the clouds
Some children laughed I'd fall for certain
For thinking that I'd last forever
Corgan always reminisces upon his past (especially his childhood) as can be seen in his LiveJournal entries
When all the fame was getting to him and the band his inner child spoke to him and laughed at the fact that he thought that moment would last forever. It was a reassuring laugh though, telling him that he would be reunited with the calmness of the past/childhood once again.
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