Black's king and d5 pawn are on the same diagonal with nothing between them. At first this might seem a minor opportunity, but in fact it is important. It means that if you take the d5 pawn and your opponent recaptures, whatever he uses for the recapture may create the kernel of a pin on that diagonal. The next question is whether you have a tool available to impose such a pin, and you do in the light-squared bishop on b5. And best of all, the only guard of the pawn is Black’s queen. So play through the capture in your mind’s eye: Nxd5; and then if Black plays QxN White has Bc4, pinning the queen and winning it after Black plays QxB and White replies d3xQ.

Again the lesson is to pay attention to enemy pawns that are pinnable. Pinning them may be worthwhile in itself; but even if not, it may be that they are vulnerable to capture because if the enemy recaptures you can pin whatever piece he uses for the purpose.