The form of Latin S occurs from Greek Σ by dropping a person out of the 4 strokes of that letter. The (angular) S-condition made up of a few strokes existed to be a variant of the 4-stroke letter Σ now in the epigraphy of Western Greek alphabets, and also https://bud-naked-concentrate08531.ampedpages.com/detailed-notes-on-s-58522304