The poem reads:
"And honored among foxes and pheasants by the gay house
Under the new made clouds and happy as the heart was long,
in the sun born over and over,
I ran my heedless ways."
These three lines reflect the theme that it is foolish to think the carefree days of youth can last because they explain how unaware the speaker is that the innocence of childhood is fleeting.
The word that helps draw this conclusion is heedless. Heedless is defined as a lack of care or attention. In this case, the speaker did not care or pay attention to the fact that childhood is fleeting.