This time White already has Black’s bishop pinned on the e-file. How should he take advantage of this? The bishop is protected by a pawn, so RxB is out. The natural idea is to push a pawn toward the pinned piece with d4-d5. Of course the pawn needs to be secure against capture, so study the squares on the pawn’s road. Here Black would be able to respond to the pawn thrust with Qxd5; but then White would play QxQ, and would Black have a reply? No, because the bishop is pinned and would be unable to recapture. So Black is better off succumbing to d5xB. The point is that when you are pushing a pawn toward a pinned target, you want to think carefully about whether it is safe on each of the squares it needs—keeping in mind that each square may be guarded by multiple attackers and defenders, but also that the pinned piece itself will pose no threat.