to answer correctly sometimes requires a good deal of instinct
trained by experience; all that is necessary if to ascertain
whether the opponent can be mated in a definite number of moves
or not. If the mate cannot be clearly foreseen, the sacrifice
must not be made. The possibility of a sacrifice with consequent
forced mate is always indicated if a greatly superior force is
available for attack at the part of the board where the opposing
King is located. An example is offered by the position reproduced
on the book cover.

[E-text editor note: The position on the book cover is:

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