The Ratical source has been debunked, see the snopes link.
Pedigree for this quote is often asserted by pointing to the 1950 Lincoln Encyclopedia, compiled by Archer H. Shaw, which "authenticates" the quote by citing a purported 1864 letter from Lincoln to one Col. William F. Elkins found in Emanuel Hertz's 1931 book, Abraham Lincoln: A New Portrait. However, this source is fraudulent: the Elkins letter reproduced by Hertz was a forgery, and Shaw, a sloppy compiler, added the bogus letter to his encyclopedia (along with several other pieces of Lincoln apocrypha) without verifying its authenticity. As historian Merrill Peterson, author of Lincoln in American Memory, noted of Shaw's work:
Read more at http://www.snopes.com/quotes/lincoln.asp#TmQ2MSs5eXjUah3P.99...
I guess I have no stake in it one way or another, but it's an interesting problem nonetheless...
It's honestly too bad none of us have real time to put into digging up and verifying this stuff on our own. The snopes source says "was a forgery...added the bogus letter to his encyclopedia (along with several other pieces of Lincoln apocrypha) without verifying its authenticity" but doesn't give reference to how this is known, or by whom it was confirmed to be a forgery.
The only other point made is that given the author's (Merrill Peterson) knowledge: "Nonetheless, Peterson concluded, even Lincoln's wartime experience and pro-labor credentials don't justify the attribution of the 'money power' warning to him".
And the other reference 'W.J. Ghent' is an article in a newspaper where he's giving what appears to be an opinion. According to his wikipedia page, he was not a historian: http://en.wikipedia.org/wiki/W._J._Ghent
It's hard to read the article given that it's scanned copy of the newspaper from 1905, but here it is: http://goo.gl/Qfsqry
So we have an argument that the letter was fraudulent without references to who asserts this, and we have the author's own authoritative "spin" as justification that the letter wasn't real.
I'm no historian, but if the "forgery" claim is based on the fact that they can't pin the handwriting to Lincoln's own, is it out of the question that the letter was transcribed?
On the other hand we have a reference which claims to contain a letter written by Lincoln, the original of which may or may not still be in existence. Who knows how far down the rabbit hole we could go just to figure this out. Instead perhaps it's best to leave it to the internet to argue the point further if they decide to.
Pedigree for this quote is often asserted by pointing to the 1950 Lincoln Encyclopedia, compiled by Archer H. Shaw, which "authenticates" the quote by citing a purported 1864 letter from Lincoln to one Col. William F. Elkins found in Emanuel Hertz's 1931 book, Abraham Lincoln: A New Portrait. However, this source is fraudulent: the Elkins letter reproduced by Hertz was a forgery, and Shaw, a sloppy compiler, added the bogus letter to his encyclopedia (along with several other pieces of Lincoln apocrypha) without verifying its authenticity. As historian Merrill Peterson, author of Lincoln in American Memory, noted of Shaw's work: Read more at http://www.snopes.com/quotes/lincoln.asp#TmQ2MSs5eXjUah3P.99...