S NO FURTHER A MYSTERY

The shape of Latin S occurs from Greek Σ by dropping one out in the four strokes of that letter. The (angular) S-form composed of 3 strokes existed for a variant from the 4-stroke letter Σ by now while in the epigraphy of Western Greek alphabets, and also the 3 and 4 strokes variants existed together with each other during the classical Etruscan