In knight discoveries, as with any other sort, groundwork often must be laid: targets improved or lines cleared with preliminary exchanges. Start with the study on the left. One of the advantages of a fianchettoed bishop (i.e., a bishop positioned like Black's on g7 here) is that if the knight comes to rest naturally on f6 (or, for White, f3), Black has the kernel of a discovered attack against the middle of the board. The pattern works especially well where, as here, the enemy king has been drawn off the back rank onto f2 or h2; for now the knight can give check with one move. All Black needs is a suitable target for the bishop once unmasked. The protected White bishop now on d4 won’t do, so Black plays an exchange to upgrade it: 1. …RxB, 2. QxR and now the board is arranged for Black to take White’s queen with the discovery Ng4+. (If White is alert he will reply to RxB by retreating his queen to c1 rather than by playing the recapture QxR,naturally preferring to forfeit his bishop rather than lose his queen and face the additional trouble that follows afterwards.)