This work is based exclusively on the observation of sacred arts: Ngombi or Ngoma (Sacred Harp), Mvet Ékang (Harp Cithare), Masque Punu, Songo (sowing game), Menorah (7-branch candlestick) and Hanoukkia (9-branch candlestick), with the current Calendar as their common point of departure. Mathematical universes are built around the recurring unity of quadrilaterals (square or rectangle) with the trilateral figure (triangle) referring to the pyramid.

They are mainly characterized by the conversation of one of the quadrilateral's diagonals into a triangular base, while excluding the second, hence the term concave geometric construction. The inner side of geometric figures is the expression of a dynamism whose evolution is both ascending and descending, under a fractal grip by the action of the arithmetic triplet.

Central symmetry, orthogonal symmetry, parallelism, perpendicularity, triangulation, diagonometry and more are just some of the geometric theorems to be found here. Civilizational memories are all revealed as bearing the same geometric framework.

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