You probably don't understand it because nobody has taken the effort to explain it to you simply. Everything I have seen on the Internet (especially programming

You probably don't understand it because nobody has taken the effort to explain it to you simply. Everything I have seen on the Internet (especially programming related sources) take a lot for granted and just spread a little code here and there. Also, a good idea is not "trying to turn your mind inside out", which is what seems to be needed from a lot of explanations I have read. It is easy, it is simple, it is normal. I am sorry I do not have a reference handy (because of the above) but those are good suggestions (otherwise I would not be writing them) that have helped me overcome similar "difficulties". Edit: Cannot help saying it. The 'a priori' and 'a posteriori' and all those terms are just fancy words (which mean what they signal) which scare a lot of people away from something, I repeat, natural.