THEME

Setting forth an idea. Often used by problemists.
Kipping, C.S.. vs Mate in 3 moves 1-0 First Prize S. Glasnik
1947.02.27

Theme Valve : The black opens a line for one of his pieces, closing another line of the same piece.
1. Qf6! Bh7
1… Ba7 2. e6 Bb8 3. Qd8#
2. Qh4 Bg8 3. Qd8# 1-0