Three tactics books

Which of these books would help me UNDERSTAND tactics and not just read " here are 10 problems to solve for pins or forks ? " Learn Chess Tactics by Nunn. Understanding Chess Tactics by Martin Weteschnik. Chess Tactics for Champions. By Polgar. I want to grow in a real understanding of the theory behind tactics. Any ideas? Other books? (My rating is close to 1400.) Stwils

Understanding tactics largely comes from doing problems.  There are some motifs that one should understand for figuring out when opportunities will arise in games, but if you aren't at the level where you can solve tactical problems at a rather rapid pace then doing problems is the best way to improve.

Chess Mentor has several excellent sets for learning some of the underlying concepts: Pins, Discovered Attacks, Back-Rank, etc.  Do the problems and read the associated text to understand the key ideas behind it.

And tactics trainer can give you exposure to some of the tactical problems without telling you which motif it lies in.

As far as the specific books you list I can't tell you which is best, but I think your approach should be to get a lot of practice with tactical problems if you're rating is 1400.

Half an hour every day trying to solve exercices.

Here with tactics trainer for example.

When you reach 2000 elo on tactics trainer, ok take a book, before I don't think we need.

Tactics is about problem solving. You can't "understand" tactics without problems.

I'm surprised no one has recommended Farnsworth's Predator at the chessboard. As far as the few tactics books I've read this has been by FAR the best and most thoroughly explained. I was able to absorb so much more than from any Pandolfini book and being free online don't hurt either.

chesstactics.org

Seems you want more talky tactics books ... which I'll admit are a minority.

The  Martin Weteschnik book is pretty darn detailed and "heavy" .. I'd start with the free Farnsworth material that the earlier post recommended.  

To pick up on the idea others have shared about just doing more problems, tactics is largely about pattern recognition, that is why they are group by "pin" "fork" etc.  You can't recognize patterns, or subtle differneces in the patterns without just seeing the patterns over and over.  there are patterns like the geometry of the board and the placement of the pieces, but there are also patterns like the right move order-- and I'm sure there are more.  Like any art, being sensative to what you see is the start-- so doing a ton of problems is the way.  I love tactics trainer here.