“From both the metaphysical and natural points of view it is false to say that in order to arrive at two, you take two ones and put them together. One only need look at the way in which a living cell becomes two. For One by definition is singular, it is Unity, therefore all-inclusive. There cannot be two Ones. Unity, as the perfect symbol for God, divides itself from within itself, thus creating Two: the creator unity and the created multiplicity.
Unity creates by dividing itself, and this can be symbolized geometrically in several different ways, depending upon how the original Unity is graphically represented. Unity can be appropriately represented as a circle, but the very incommensurability of the circle indicates that this figure belongs to a level of symbols beyond reasoning and measure. Unity can be restated as the Square, which, with its perfect symmetry, also represents wholeness, and yields to comprehensible measure. In geometrical philosophy the circle is the symbol of unmanifest Unity, while the square represents Unity poised, as it were, for manifestation. The square represents the four primary orientations, north, south, east and west, which make space comprehensible, and it is formed by two pairs of perfectly equal yet oppositional linear elements, thus graphically fulfilling the description of universal Nature found in Taoist and other ancient philosophies.
The square (above) represents the earth held in fourfold embrace by the circular vault of the sky and hence subject to the ever-flowing wheel of time. When the incessant movement of the universe, depicted by the circle, yields to comprehensible order, one finds the square. The square then presupposes the circle and results from it. The relationship of form and movement, space and time, is evoked by the mandala.”
Source: Robert Lawlor, Sacred Geometry: Philosophy and Practice, pp. 16, 23