What are the symbols of duality in Freemasonry?

The mosaic pavement, or chequer floor-work, is an old symbol of the lodge whose black and white stones represent the dualities of human existence 12. Mackey notes that its parti-colored stones are interpreted as symbols of the evil and good in human life 1. Wilmshurst expands on this dualism, viewing the chequered pavement as representing the world of opposites—light and darkness, good and evil, joy and pain—upon which every living being walks 2. He further contrasts the physical floor of the lodge with its celestial canopy above, viewing the ground and the ceiling as opposing poles reflecting man's earthy sensuous nature against his ethereal spiritual nature 2.

The twin Brazen Pillars situated at the porchway entrance also carry symbolic associations of duality 3. Claudy records that among various interpretations, some writers have suggested the two pillars represent the masculine and feminine elements in nature, while others hold that they stand for the dual authorities of Church and State 3.