In the Four Pawns Attack...
Black takes this pawn
White takes this pawn
Black replies by moving this Knight
Attacking this pawn
White defends it by moving this Bishop here
Then, Black moves his light-squared Bishop
White replies by moving this Knight
Black moves this pawn forward
White moves this Knight
Black replies by moving this Bishop
White moves this Bishop
Black castles Kingside
To protect his King
White castles too