I am intimately familiar with this Mark Twain item. A.B. Paine wrote about
it briefly in his 1912 Biography, and it is a small collection that Mark
Twain himself assembled (patent medicine advertisement & a note by Twain and
a dictation signed by him) which came into my possession several years ago.
The quote in question, which contains errors from the original dictation
hand written by Isabel Lyon and signed by Mark Twain, stems from an
autograph dealer that I sold the collection to. The radio broadcast
repeated the autograph dealer's errors, namely the incorrect word
"Profession" somehow replaced the correct "procession", and the incorrect
"gamered" is substituted for the correct "earned." If you read it correctly
you will find this makes infinitely more sense. Thus, the radio source was
an autograph dealer catalogue. The Twain quoted was an UNMAILED response
to the Elixir company , who sought Mark Twain's endorsement for the elixir.
Often Twain is at his best this way, writing or dictating letters never
intending to actually mail them.
I am making these corrections from memory, so there may be more subtle
corrections to be made, and my notes aren't handy at the moment. As far as
authenticity goes, you can rest assured the item is genuine Mark Twain. I
have specialized in Mark Twain's handwriting for nearly two decades, and
represent the only business that exclusively deals in rare Mark Twain
memorabilia--which is the only entity in the world that offers a double
money back authenticity guarantee for handwritten material.