The 'straight' is to 'curve' as the 'square' is to 'circle.' Andrew's list has 'rectangle which could be thought of as a dualism also in the effort to figure out how the 'one' becomes the one, from the two. You just have to be able to explain the symbolism, or the applicable point. This of course becomes problematic as these connotations of dualism (duelism) can change in the perceptions of both the individual and culture.
Another problem for figuring out the relationships in dualism is they are not always 'duelism,' or opposites.
For instance in Leonardo DaVinci's famous human figure drawing 'Vitruvius,' Leonardo has the figure inside both a square and a circle. He states that the architecture of man is arranged by nature. Four fingers make one palm, four palms make a foot, six palms make one cubit, four cubits make a man's height, four cubits make a pace, and 24 cubits makes a man's height. (I tried this and find it not so, but I am an odd size maybe?) Ref. "Images of the Universe' by McLanathan, Doubleday, 1966.
As near as I can figure the circle and the square symbolize balance and harmony, which are not opposites.
What is the answer? I would look for it in the GThom, saying number two:
Th-2. Jesus said, "Those who seek should not stop seeking until they find. When they find, they will be disturbed. When they are disturbed, they will marvel, and will reign over all. [And after they have reigned they will rest.]"
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