if the Knight moved. (4) ..., P-d6 or Q-e7 is not a sufficient
defense, for White continues with (5) P-f4.

+---------------------------------------+
8 | #R | | #B | #Q | #K | | | #R |
|---------------------------------------|
7 | #P | #P | #P | #P | | #P | #P | #P |
|---------------------------------------|
6 | | | #Kt| | | #Kt| | |
|---------------------------------------|
5 | | | #B | | ^P | | | |
|---------------------------------------|
4 | | | ^B | #P | | | | |
|---------------------------------------|
3 | | | | | | ^Kt| | |
|---------------------------------------|
2 | ^P | ^P | ^P | | | ^P | ^P | ^P |
|---------------------------------------|
1 | ^R | ^Kt| ^B | ^Q | | ^R | ^K | |
+---------------------------------------+
a b c d e f g h

DIAGRAM 31.

Pieces that can be used for pinning a hostile man are, apart from
the Rooks, the Queen and the Bishops; in fact pinning is the main
activity of a Bishop throughout the game. Right after the first
few moves one of the Bishops, as a rule, finds an opportunity to
pin a hostile Knight. For instance: (1) P-e4, P-e5; (2) Kt-f3,
Kt-c6; (3) B-b5 and as soon as the Pawn d7 moves in order to give