Before entering on the second half of this section we must devote a few words to artificial methods of moving the body, which are divided into two classes, those which are passive and those employed in active locomotion. Naturally the first implement of this kind to be mentioned is the cradle, of whose use among the Greeks we find no evidence, but the Romans had them since the time of Plautus. The oldest German record of them is in the Saxon manuscript at Heidelberg.[195] Of course, the cradle’s rocking motion and its soothing effect should be included in our enumeration of agreeable movements. The same may be said of swinging, which we find practised by many birds and by the ape; indeed, one case is recorded where a monkey himself attached a rope to the projection of a roof and swung himself on it. The human race, too, probably without exception, enjoy the sport. The hammock is in some cases the prototype of the swing. Von den Steinen relates of the Brazilian Bakairi that the men when at home spend most of their time swinging in hammocks.[196] Parkinson describes a still more primitive sort of swing. It seems that the Gilbert Islanders select a stout, well-grown cocoanut tree and attach a cord to it, on the other end of which is a club. A young woman climbs on the trunk, and taking her seat there is swung by a youth, who, watching his chance when the motion is well under way, catches hold with his hands and swings with her.[197] The Greeks had several forms of the swing, among them the joggling board, consisting of a flexible plank supported at its ends on fixed beams, and the rope swing which with its comfortable seat supported by four cords was used by adults. The Berlin Museum possesses a bowl ornamented with the figure of a fawn running under a young girl in such a swing and sending her high in the air. Athens celebrated a special holiday called after the swing, αἰῶραι.[198]