Most of the final volume in Ishida's wonderful series is about the 4-4 opening. This is particularly important because of the handicap rules.
Unlike chess, Go is fortunate in having a natural handicapping system, which works well and is in common use. At the start of the game, the weaker player is given up to nine extra stones, the number depending on the difference in strength. The first four are placed on the 4-4 points, the next four on the fourth-line points intermediate between two corners, and the last one on the central point. The following diagram shows the handicap points.
Recall that fourth-line stones don't take territory on their own, since the opponent can slide underneath them. If you don't believe this, here's one of the most important joseki (corner openings). Black started on 4-4, but White plays at 3-3 (stone number 1):
Now Black blocks White with 2, but White begins building his little territory with 3. Black can then continue at points a, b or c. The first of these is most usual, after which play typically goes on like this:
As you can see, White has got his territory in the corner (the Substance), but it is hard for him to make it any bigger. Black has a wall on the outside (the Shadow), which is his compensation.
The thing that's so nice about the handicapping system is that Black, in order to use his extra stones, has to play this way. He must get the Shadow and attack. White, who will have superior tactical skill, tries to intimidate Black into playing passively, but if he does he will most often lose. Volume 3 is full of exhortations to the weaker player to believe in himself and his stones, and be aggressive. You suddenly understand why the Samurai were so keen on Go - it was one of the four traditional Samurai arts.
I hope I've convinced at least a couple of people to check out this amazing new world! And then read The Master of Go or Shibumi. They're both fun books, in completely different ways.