After looking through hundreds of books on pool and billiards from 1807 until 1978,I believe that there was very little "correct" information about how to play pool available. Mingauds 1827 work had a treasure chest full of ideas and concepts which you could incorporate,{he actually invented nearly every concept we use today} but how many people would have even known to look for it?
imo with the exception of George Fels book, most of the books were basically, misinformation. All copied from the same incorrect or incomplete source.
About the only way to get knowledge was to befriend a good player and hope they were one of the few who would show you.
If you go back in the history of players you can just about follow a who's who of pool progression of their mentors by the area the grew up in.
There were very few exceptions.
Jump forward to Bob Byrne, Ray Martin, Phil Capelle, all the Dvds all the free stuff from Dr. Dave all great information and myriad other sources available now, that anyone who can read can utilize.
I believe that is why there are so many great players from all over the world today.
I have written in another thread that I overheard a converstaion between Jim Rempe and another pro one time about backhand English in the early 1970s. Bert Kinnister says they wanted to strangle him when he gave up that "secret".
Understandaby so, it is a powerful weapon you can use to get the cueball to places on the table you can't any other way. {At least that I have seen}.
I will never forget the day I learned how to put force follow on the cueball next to the rail, at the time it was probably worth almost a ball at my One Pocket game! Just that one shot!
How about drag draw?
I learned that on my own and didn't know what it was called in the 60s.
I used it waaaaay too much for about 5 years but it is a huge shot to know for beginners.
Every shot or move has a value, I showed a great player a shot when I was in Phoenix he didn't know, he said he valued it at 1/10th of a ball.
He's a very fine player, much higher skill level than me , so it must have been a potent shot to make that much difference.
Of course, it makes sense, because I learned it from a great player named George Rood.
Every shot , move, stroke , trick , that you learn has a value to be put in your overall game.
I am sure there are still some "secrets" that have not been given out, but I believe there is enough information available to anyone with good comprehension , great eyesight and decent nerves to become a high level player.
All of you guys 40 years old and under should send a thank you note to Bob Byrne, he started the information flow, without it , most of you would still be hacking around like you see the old timers.