In Vain by Jack Kerouac

I think this poem has different ways to undestand it, that's why I think it is quite hard to explain. 
First of all it repeats a lot the phrase "in vain" every time it says something before... 

The stars in the sky

In vain

The tragedy of Hamlet

In vain

I believe that what the author wants to say is something like "anything in life is not worth it", or also it can be something like "everything that has happened for what?" 

Abraham Lincoln 

In vain

The Aztec empire

In vain

It is even more difficult to know what the author wants to say because it mentions a lot of different things, in nature, art, and history. When I read the parts about history I think that the author is saying that in the end all those fights and time of government was for nothing because society forgets about things, what also makes me think of ignorance.