Interestingly (and the author stresses this emphatically in the introduction), the "secret" cannot be merely doled out like dollars - a great willingness/eagerness to uncover it is required for it to be of any use. Had the passage been merely dropped in my lap without any context or deep inquiry, I doubt it would have been of any use.
Thankfully, the book itself can be had for free online from a number of sources, including this one found via a quick Google search: http://www.onestopinternetbusiness.com/tgr.pdf
Here are a few relevant passages from the introduction:
"The secret to which I refer has been mentioned no fewer than a hundred times, throughout this book. It has not been directly named, for it seems to work more successfully when it is merely uncovered and left in sight, where THOSE WHO ARE READY, and SEARCHING FOR IT, may pick it up. That is why Mr. Carnegie tossed it to me so quietly, without giving me its specific name. If you are READY to put it to use, you will recognize this secret at least once in every chapter. I wish I might feel privileged to tell you how you will know if you are ready, but that would deprive you of much of the benefit you will receive when you make the discovery in your own way."
"The secret to which I refer cannot be had without a price, although the price is far less than its value. It cannot be had at any price by those who are not intentionally searching for it. It cannot be given away, it cannot be purchased for money, for the reason that it comes in two parts. One part is already in possession of those who are ready for it."
"Somewhere, as you read, the secret to which I refer will jump from the page and stand boldly before you, IF YOU ARE READY FOR IT! When it appears, you will recognize it. Whether you receive the sign in the first or the last chapter, stop for a moment when it presents itself, and turn down a glass, for that occasion will mark the most important turning-point of your life."