	Take a complete graph "K". It has 15 edges, 15 perfect matchings and 20 triangles. Create a point for each of the 15 edges, and a line for each of the 20 triangles and 15 matchings. The incidence structure between each triangle or matching (line) to its three constituent edges (points), induces a PG(3,2). (Sylvester's work on duads and synthemes, 1859)