God, or the One of the Universe (Unus mundi, in Latin) or the divinity, is represented as a circle.
A second circle forms, representing Duality. The soul temporarily separates from the One (Unity) to know herself.
There is a spiritual journey of the soul from Unity to Duality and then back to Unity.
The two segments form a cross. This cross represents Christ and the concept of Trinity, as witnessed by the ratio of the squared lengths of these segments, which is number 3, i.e., the number of Trinity. The Vesica Piscis migrated from the Pythagorean philosophy, where it was a Triad, to the Christianity becoming a Trinity