Now a position from Paulsen-Morphy (1857). The mating idea for Black is not obvious; White’s king seems secure, does it not? That is what makes Morphy’s play of it astounding: he begins with 1. ….QxB—a quite expensive sacrifice to force open the White king’s pawn cover. The arrival of the queen on f3 creates a variety of eventual mate threats, so of course White takes it with 2. g2xQ. Black’s immediately follow-up is obvious enough: seize the now-open g-file with his rook by playing 2. …Rg6+, forcing 3. Kh1. At this point you might be a little puzzled; where is Black’s light-squared bishop? It isn’t posted on the long diagonal, and moving the c6 pawn forward to make room for it will lose too much time. Morphy’s solution to this problem was 3. …Bh3. That brings us to the next frame.