A Poem with An Allusion

Nature's first green is gold, 
Her hardest hue to hold. 
Her early leaf's a flower; 
But only so an hour. 
Then leaf subsides to leaf. 
So Eden sank to grief, 
So dawn goes down to day. 
Nothing gold can stay.     

What is the allusion why did they use it and what you like about the poem 

The allusion if this poem is the story of Adam and even in edens garden and how they were living great until eve had eaten a fruit from the tree that they weren't supposed to eat from.  They used this allusion because they wanted to get the point across that no matter how good something seems it will always fade and that nothing good last forever.  The things that I like about this poem is the message that it sends.