When designing a universe you need triangles to create self-supporting structures. Carpenters stabilize structures by bracing it with triangles. Triangles provide strength, balance and efficiency of energy space and materials. Many knots and braids utilize the principle of the triad for strength and self-reinforcement. All color photography is the blending of three basic colors, yellow, magenta and cyan.
Nature uses triads fluently.
Notice how the triad is the basic design in the butterfly to the left. The right thing is to proceed from second dimension to third, which brings us, I suppose, to cubes and other three dimensional figures. Plato The tetrahedron is the simplest four sided solid composed of perfect triads. The number four is the beginning of depth in space. The number four is the mother of three-dimensional form.