text: Posidonius divides the arts into four classes: first we have those which are common and low, then those which serve for amusement, then those which refer to the education of boys, and, finally, the liberal arts. The common sort belong to workmen and are mere hand-work; they are concerned with equipping life; there is in them no pretence to beauty or honour. The arts of amusement are those which aim to please the eye and the ear. To this class you may assign the stage-machinists, who invent scaffolding that goes aloft of its own accord, or floors that rise silently into the air, and many other surprising devices, as when objects that fit together then fall apart, or objects which are separate then join together automatically, or objects which stand erect then gradually collapse. The eye of the inexperienced is struck with amazement by these things; for such persons marvel at everything that takes place without warning, because they do not know the causes. The arts which belong to the education of boys, and are somewhat similar to the liberal arts, are those which the Greeks call the "cycle of studies," but which we Romans call the "liberal." However, those alone are really liberal – or rather, to give them a truer name, "free" – whose concern is virtue.