Descendisse autem, dum fit, videtur et subit oculos. Probably this bit of characteristic Latinity had better be rendered thus: “The accomplishment of a descent, however, is, whilst happening, a visible process, and one that meets the eye.” Of the various readings, “dum sit,” “dum it,” “dum fit,” we take the last with Oehler, only understanding the clause as a parenthesis.