You will please note that this is not directed to the casual reader, but is intended for the serious, psychologically and philosphically articulate. For background reading, I recommend Helen Haste's The Sexual Metaphor, and Hargrave Jennings' Phallicism .
Unity and Duality
For artists, poets, and philosophers, there is no end to the symbols, ranging from basic representitive art to very subtile literary, geometric and architectural forms that have been utilized to express the philosophical notions of Unity and Duality; many of them are sexual in nature. By that I mean that they employ or are based on the (visual and verbal) language of the male/female dichotomy that pervades our daily life.
Unity is almost universally depicted as a circle, and as column shaped objects (the column being derived from a circle, the circle is an abbreviation of the column, so to speak), the number 1 and the letter I, masculine symbology, while duality is depicted as a vesica, a divided circle, symbol of division, the cause of multiplicity, is deemed to be female. Albert Pike refers to these as the monad and duad.
Every thing in God's creation is ruled by the idea of duality; or we could say that the mind frames things dualistically. As G.F.W. Hegel points out in his "Phenomenology of Mind", even our notion of Identity, x equals x, is dualistic, and contains in it the idea of division; just as a seed contains within it a tree. Of course, the phenomenological ground of our understanding of identity is our experience of self consciousness, in which one part of our Self "grasps" another part, and recognizes the unity of the two. Consciousness realizes that both the I and myself, in "I am myself", are parts of the same Self. The anthoromorphising human mind projects these categories onto the World and God.
In the statement of self consciousness then, we can see three elements, the subject (the Transcedental Ego that can never be an object, that does the grasping so to speak), the object of consciousness, and the relationship between the two, in this case the "am" as a statement of Identity.
The Transcendental Ego relates to the "outside world" as a "not me"; that is the self is the "not thing" or nothing that provides the background for the world of objects. This is the experiential basis for our notion of the Transcendent God as the Ground of Being, the bare possibility of being, Being not yet opposed by not being.
The three elements spoken of above are represented by the Holy Trinity, where the Father is the original Unit (prior to division), the One; the Son is the Word made flesh, the sum of the created world, the multiplicity of forms; and the Holy Spirit is the Mystical (conceptual) Unity of these forms, the return to the Unity condition (symbolized by the phrase "ex pluribus unum", one from many).
Yin and Yang
This trinity of form is symbolized by the familiar yin/yang/Tao symbol, the purest expression of this dialectical structure, representative of the inter-penetration, strife and unity of opposites. Inter-penetration refers to the fact that the white half has a black center, and the black has a white center, because the meaning of each is tied to the meaning of the other; they are what we call compliments. The meaning of the word "hill" is tied up with the meaning of the word "valley", just like in and out, up and down, and male and female.
Strife refers to the fact that only one thing can occupy a space at one time. The light is either on or it's off; you are either going in or out, but not both at once. Unity refers to the fact that together the two ideas complete each other, they form a synthesis, whose meaning is greater than the sum of it's parts. This then, is the meaning of the dialectic formula of thesis, opposed by an anti-thesis, which when the two are "balanced and transposed" produce a syntheis.
The Tao, and the yin and yang, are the Triple Crown of the Tree of Life from the Kabbalah. The Tao is the Source from which everything emanantes and to which All return; while the yin and yang represent the first two emanations, viewed as the Mother and Father of the generated world. Note that, in dialectical terms, movement away from the One (down the Tree of Life) is what we call analysis that depends on division and results in multiplicity, while movement toward the One (upward on the Tree) is called synthesis, a unifying process. Analytically then, we can see the yin and yang as the first twin products of the Fall from the Paradise of the One, while sythetically, they are the last opposition to fall away at the Redemption or Return to paradise, the Kingdom of God. The related alchemical term is "solve et coagula". First we volitalize the fixed, then we fix the volitile.
Male and Female
In her book entitled "The Sexual Metaphor", Helen Haste points out that we inhabit an engendered world, and that gender is the primary category of our social relations. The book, written from a feminist perspective, revolves around the notions that "we reflect and reproduce this categorization" in language, and in the symbols and metaphors that we use, and that we tend to map other dualities on to metaphors of masculinity versus femininity.
Haste points out that ideas about the inequality of the sexes are perpetuated when we make dichotomies like rational and irrational, order and chaos, deductive reasoning and intuition analogous to the male and female dualism. Terms like rational and order are construed as being positive, and are associated with masculinity, while irrational and chaos have negative connotations, and are associated with femininity. We see, for instance, that a rational deductive approach to science is called "hard science".
In his Experimental Essays (1661), English scientist Robert Boyle distinguished between merely knowing as opposed to dominating nature in thinly veiled sexual metaphor: "For some men care only to know nature, others desire to command her" and "to bring nature to be serviceable to their particular ends, whether of health, or riches, or sensual delight."
The writing of Roger Bacon carried the theme a bit further, and contains metaphors of both sexual persuit and rape; "For you have but to hound nature in her wanderings, and you will be able when you like to lead and drive her afterwards to the same place again. Neither ought a man to make scruple of entering and penetrating into those holes and corners when the inquisition of truth is his whole object."
Thus Boyle and Bacon outlined the key features of the modern science in the sexual imagery of constraining of nature, and the penetration of her hidden secrets, for the good of "man".
The Compass and Square
If you look at the figure of the Masonic compass and square, you will see that it closely resembles the Star of David, which is composed of two inter-twining equilateral triangles; both of these depict the sexual union of the masculine and feminine forces of the created Universe, the generative forces. The square, in the lower position, represents the feminine aspect of Creation, while the compass represents the masculine aspect.
The Masons map a whole complex of other dualities onto this emblem. The currently accepted religous metaphor sees a masculine god (called the Father) occupying the upper region (called heaven), while the lower region, the earth is personified as the Mother. While the female is depicted as being passive, the male sky god's activeness is figured as rain and lightning descending to earth from on high.
[Please note that the earth was not always associated with the female.You may recall that Osiris was the son of Nuit, the Sky Goddess and Geb, the Earth God (pictured above), so that the earth was seen as striving upward (as the Djed pillar, or the axis mundi) toward the female, rather than "raining down" on the earth, as we now see it. The existence of obelisks and church steeples seems to be an archetypical fragment from that era.]
To the Masons, the square is associated with geometry, literally earth measure. The square, both as a mason's tool and a geometric figure, as well as the cube and the number four (as in the four seasons, the four winds and directions, and the four elements) are all connected with the earth and materiality. Generalizing a bit we get connections to matter, physicality, and the body.
On the other hand, the compass, the circle and the sphere, are all connected to notions of the spiritual and mental realms. The compass on top of the square, illustrates the notion of "mind over matter".
Not only is the square in the lower position in the sense that the compass occupies the top space in the figure, but also in the sense that the compass lies on top of the square. In his section on the 32nd Degree of Scottish Rites Masonry, in his book "Morals and Dogma", Albert Pike alludes to the Royal Secret of Alchemy in the sexual metaphor of the "Mystery of Balance" or the "Secret of Universal Equilibrium". Using language that drives feminists crazy, we read (p 854):
"One definition of Freemasonry is symbolized by the Compass and Square. For the Apprentice, the points of the Compass are beneath the Square. For the Fellow-Craft, one is above and one beneath. For the Master, both are dominant, and have rule, control, and empire over the symbol of the earthly and material.
Every Degree teaches that the noblest purpose of life and the highest duty of man are to strive incessantly and vigorously to win the mastery of everything, of that which in him that is spiritual and divine, over that which is material and sensual."
[See "Under My Thumb" by the Rolling Stones.]