LONG I thought that knowledge alone would suffice me--O if I could 
         but obtain knowledge! 
   Then my lands engrossed me--Lands of the prairies, Ohio's land, the 
         southern savannas, engrossed me--For them I would live--I would 
         be their orator; 
   Then I met the examples of old and new heroes--I heard of warriors, 
         sailors, and all dauntless persons--And it seemed to me that I 
         too had it in me to be as dauntless as any--and would be so; 
   And then, to enclose all, it came to me to strike up the songs of the 
         New World--And then I believed my life must be spent in 
         singing; 
   But now take notice, land of the prairies, land of the south 
         savannas, Ohio's land, 
   Take notice, you Kanuck woods--and you Lake Huron--and all that with 
         you roll toward Niagara--and you Niagara also, 
   And you, Californian mountains--That you each and all find somebody 
         else to be your singer of songs, 
   For I can be your singer of songs no longer--One who loves me is 
         jealous of me, and withdraws me from all but love, 
   With the rest I dispense--I sever from what I thought would suffice 
         me, for it does not--it is now empty and tasteless to me, 
   I heed knowledge, and the grandeur of The States, and the example of 
         heroes, no more,                                             10 
   I am indifferent to my own songs--I will go with him I love, 
   It is to be enough for us that we are together--We never separate 
         again.
Walt Whitman
http://www.poemhunter.com/poem/long-i-thought-that-knowledge/