He gave me the basic idea of how a knife edge was the result of the blade being ground away until a sharp edge was there. He did explain how the lower the angle the better a knife would cut. Believe it or not that's all you really need to know. Create an edge, remove any burrs and start cutting or put the knife in your pocket. That was really about it.Having said that there's more to it along with mainly a LOT of practice. Especially if you want to learn to free hand sharpen. This is all just my opinion of course.
With Dad's teaching and practice by the time I was in high school I could get any knife sharp enough to shave my arm and amaze my friends. Back then just about every boy in high school carried a pocket knife everywhere.
About 10 or 12 years ago I got into sharpening a knife at a higher level. I use an Edge Pro exclusively for 2-3 years. That is a great sharpening system. With it I learned how to recognize to a certain extent the angle of an edge when someone shows me their knife. Great system. If you own one you have a great setup if you ask me. Or a Wicked Edge. Never used one but the videos are great.
Then just for fun I decided to learn to free hand sharpen at a higher level. Keep in mind, with my set of two Smith stones (medium and fine I think) I could easily shave my arm hair and that's sharp enough for about any pocket knife and a bunch of knife for special uses. With the Edge Pro I was able (after a while) to get a knife sharp enough to whittle a single strand of my own hair. Just in case you don't know what "whittling a hair" means, take a stick and cut into it and notice how the wood curls up. This is done a lot to help start camp fires. Picture doing that to a single strand of hair without cutting all the way through it.
Now I can do that with a set of bench stones. I have DMT extra-course thru extra-fine, Spyderco medium thru ultra-fine and also a complete set of Shapton glass stones (320-16k). If I were to need to get on a plane and go somewhere I'd take my Spyderco medium and fine grit stones and have all I need to maintain my own pocket knives as well as any frined's knife as long as it wasn't super dull.
So if you are just now starting to learn to sharpen a knife and you are on the internet I'm sure you are bombarded with which system or way to sharpen to learn. I have opinions on how to answer this question. That means how to spend your money and use your time learning how to use the tools you buy.
My hands on experience: Childhood; free hand with the same set of stones for about 20 years. Stones I put oil on. The last several years these stones were worn and clogged but I didn't know enough to know that. Then I got a DMT aligner. Great set for getting a very, very sharp knife but the clamp won't hold every knife the same. This single issue prompted me to get the Edge Pro. MUCH better system with much more control. Then on a whim I decided to improve my free hand sharpening skill.
A set of Spyderco stones cost about $150 I think if you include the ultra-fine stone. But, 99% of people don't need that grit for just forget about it and consider a set of Spyderco's under $100. A set of DMT stones will be somewhere in the same ballpark or higher if you want more grits. Personally, if you get Spyderco stones I'd recommend a course DMT for a stone to remove more steel faster for very dull knives. I have Shapton glass stones and love them. However, based just on cost I'd get the DMT or Spyderco stones. Two reasons. 1. Less expecsive (BY A LOT). 2. I use the Spycerco and DMT stones much, much more. Also, the DMT and Spyderco stones don't require any water. Just pull them out, use them and put them back. DON'T FORGET, you need to clean them which takes about 3 minutes with Barkeeper's Friend (or Comet) and a scrub brush.
What I have come to think is with systems that control the angle for you, you can lean them faster and have VERY sharp knives. But when you don't have that system on you and you need to sharpen a knife you may be somewhat lost. But, you can learn to use the systems very fast.
With free hand sharpening, it takes a little longer to learn to control the angle but you can take a stone or two with you anywhere and are always ready. Or you can use the stones that happen to be wherever you happen to be if there are any there.
Keep in mind, when I was 11 years old my Dad taught me to sharpen a knife on one or two stones and I was shaving my arm for as long as I can remember.
Just my thoughts. Take care.
Jack
where in the world does the average layman need a 16,000 grit Shapton water stone? 
Yes I have watched videos on fine kitchen/restaurant chefs knives and sharpening them, some costing over a $$$grand. If I was manufacturing surgical scalpels maybe. Sometimes we have taken Norton stones to the ultrasonic cleaner to get the debree out of them. I once watched a man sit and sharpen a block plane blade with the scary sharp method. A piece of scrap plate glass with wet or dry paper fastened to it. Well maybe that if I was making very fine furniture with a $500 and up block plane.
but I am able to get the kind of toothy edge which I like on hunting and kitchen knives with my EDGE-PRO setup. Smaller knives are harder for me to put in order but I sorta get by with a potpouri of free-hand stones and my EZE-LAP diamond hones which nest inside themselves in a brass casing. Stainless steel blades are the most frustrating to me. I would like to know more about this Lansky system- Is it workable for the smaller blades in pocket knives?
