"And what checks would I then have?" Learning to ask this question consistently is one of the secrets of great chess. This position offers two illustrations.

The idea here is similar to the previous position but with a slight upgrade in complexity. Again White’s knight prevents him from playing QxQ; again the knight is not yet in position to give check; and again Black’s king is hemmed into the corner by the bishop on h6. The question is whether the knight on d4 can take advantage of the king’s vulnerability in a way that requires Black to make a time-consuming reply. As in the previous position, look for places the knight can move that would place it one move away from giving check, and then consider the consequences of that potential check to see how bad it would be for Black.

Here the knight can start by moving to c6 (with a capture) and then be a move away from Ne7+—while also unmasking the threat of QxQ. Suppose Black replies with QxQ, and now White plays NxNe7+. How serious a threat would that be? Black’s only legal move would be Kh8; White looks for his next check and finds that he can mate by bringing in another piece: he moves his g5 knight to f7. So if White starts with NxNc6, Black can’t afford to play QxQ. Can he afford to instead play QxNc6? That seems to extinguish White's threat against e7. But again White asks what checks he then would have and sees that this time Qg7 would be mate. (Black's queen was doing important defensive work on f6.) So NxNc6 wins either way.