It is the greatest weakness of the Bishop, that when the Rook's Pawn Queens on a square of opposite colour and the opposing King is in front of the Pawn, the Bishop is absolutely worthless. All that Black has to do is to keep moving his King close to the corner square.
Example 31.—In the above position White with or without the move can win. Take the most difficult variation.
| 1. ........ | K - R 7 | |
| 2. Kt - Kt 4 ch | K - R 8 | |
| 3. K - B 1 | P - Kt 4 | |
| 4. K - B 2 | P - R 7 | |
| 5. Kt - K 3 | P - Kt 5 | |
| 6. Kt - B 1 | P - Kt 6 ch | |
| 7. Kt × P mate |
Now that we have seen these exceptional cases, we can analyse the different merits and the relative value of the Knight and the Bishop.
It is generally thought by amateurs that the Knight is the more valuable piece of the two, the chief reason being that, unlike the Bishop, the Knight can command both Black and White squares. However, the fact is generally overlooked that the Knight, at any one time,
has the choice of one colour only. It takes much longer to bring a Knight from one wing to the other. Also, as shown in the following Example, a Bishop can stalemate a Knight; a compliment which the Knight is unable to return.
Example 32.