The shape of Latin S arises from Greek Σ by dropping just one out of the 4 strokes of that letter. The (angular) S-condition made up of a few strokes existed being a variant with the 4-stroke letter Σ by now during the epigraphy of Western Greek alphabets, and also https://donovanmeuix.eedblog.com/31381073/5-easy-facts-about-bud-naked-flower-described