To support the advance of the Kt P.
17. Kt to Kt 3 17. P to Kt 4
18. Kt to B 5 18. P to B 5
It is an essential point in the defense to prevent White's Knight from
being posted at K 6. If White is able to {367} accomplish this, his
attack becomes so powerful that it cannot be withstood. It would,
therefore, be bad for Black to play, instead of the move given in the
text, 18.... B takes Kt, because of 19. P takes B, Kt to K 4; 20. B
takes Kt, B P takes B; 21. Kt to Kt 5, followed by 22. Kt to K 6 (the
dangerous move just pointed out).
Black.
+---------------------------------------+
| | #R | #B | #Q | | #R | #K | |
|---------------------------------------|
| #P | | #B | | | | #P | #P |
|---------------------------------------|
| | | | #P | | #P | #Kt| |
|---------------------------------------|
| #Kt| #P | | ^P | | ^Kt| | |
|---------------------------------------|
| | | #P | | ^P | | | |
|---------------------------------------|
| | | | | | ^Kt| | |
|---------------------------------------|
| ^P | ^B | | ^Q | ^B | ^P | ^P | ^P |
|---------------------------------------|
| | | ^R | | | ^R | | ^K |
+---------------------------------------+
White.
FIG. 9.
[POSITION AFTER WHITE'S 19TH MOVE.]