How does duality manifest in Masonic teachings?

Wilmshurst takes duality in Craft symbolism to represent the fundamental condition of human existence and consciousness, most prominently illustrated by the chequered floor-work and the physical structure of the lodge 1. The black and white square pavement symbolizes the dualistic world of temporal opposites—good and evil, joy and pain, and man's material or sensuous nature 1. Every action in life occurs upon this pavement, but "walking upon" it signifies transcending and dominating these lower opposites, keeping them under subjection to cultivate inner serenity and spiritual capacity 1.

In sharp contrast to the black and white floor, the ceiling or covering of the lodge—described as a celestial canopy—typifies man's ethereal nature, serving as the opposite pole to his material body 1. This polarity is further reflected in the spatial alignment of the lodge itself: the East represents man's highest spiritual consciousness, whereas the West symbolizes his normal rational understanding employed in mundane, daily affairs 1.

Duality also manifests in the interaction of the working tools placed upon the Sacred Volume 1. Wilmshurst interprets the Square as a downward-pointing Water Triangle representing the passive soul, while the Compasses form an upward-pointing Fire Triangle symbolizing active spirit and functional energy 1. The interlacing of these two tools reflects the interaction and balancing of passive and active principles, where the aspirant gradually transmutates passivity into active spiritual energy as he progresses through the degrees 1.