Who wrote the lines of poetry "quoted" by Lincoln at the Soldiers' Home?

[RJNorton]

Thank you very much, David. I did what I think was a pretty thorough search for those words in other works, and I drew a blank. The only logical conclusion I could come up with was as you proposed - that Lincoln himself devised the words.

This doesn't totally preclude the possibility that a poem exists that contains these exact words, but I could not find it. My money is definitely on Lincoln at this point.