Look for loose Black pieces and you find both the bishop at b4 and the bishop at g4. White’s queen has no checks that can be paired with attacks on either bishop, so he looks to his other pieces to help. The goal is a check that will draw the king out where it can be attacked at the same time as one of the bishops. The natural check to try first is one using White’s bishop, since that also vacates c4 and makes it available for the queen. Hence 1. Bxf7+; and then if Black replies KxB, White has 2. Qc4+. This attacks the king and both Black bishops, winning one of them and gaining a pawn.