 Others, following Mommsen, take the view that Celsus was using the ordinary Latin (and English) meaning of "posterior".A third view is that neither half of the 48-hour "bis sextum" was originally formally designated as intercalated, but that the need to do so arose as the concept of a 48-hour day became obsolete.There is no doubt that the bissextile day eventually became the earlier of the two days for most purposes.