Figure 2.2.2.10[White to move]

Now a defensive study. White is about to play BxN, which looks safe. But consider the board as it would appear after the capture. Ask what White pieces would be left loose and you find the bishop then at b3. Ask what checks would Black have, and especially any that also would attack the bishop, and you find Qb6+, which would win back the lost piece after White moves his king.