Figure 4.3.6.4[White to move]

White can inflict a classic pin of the enemy queen with his rook, playing Re1 and drawing protection from his own queen on c3. The dangers present in the previous position are absent here. But you also must concern yourself with another possibility: your opponent may be able to give check and attack your pinning piece at the same time. So White considers every check Black could give in reply to 1. Re1, and actually there is just one: Bxf2+. This is a bishop fork and it would indeed be a disaster for White. He wouldn’t legally be able to take the bishop with his king, so he would have to move the king away; and then Black would have a move to play BxR, winning a piece, ending the pin, and attacking White’s queen to boot. So the pin of the queen here is not a good idea after all. (The right move for White is Rd2, defending the rook and f2.)