Celsus, whose description of the operation is famous, gives us no more hint of the shape of the lithotomy knife than Paul does. He only says 'multi hic scalpello usi sunt', and as he uses 'scalpellus' to denote all sorts of different knives, we can draw no information from that term. We may note, however, that both Celsus and Paul describe the operation as being performed by fixing the stone by means of the left index finger inserted in the anus, and cutting down directly upon it with one stroke as in opening an abscess. Now this sort of incision was always performed by early surgeons with a two-edged scalpel sharp at the point, and a knife of this sort was used for lithotomy by the Arabian surgeons, and after them by European surgeons down to comparatively recent times. Heister, for instance, shows as a lithotomy knife a large knife, like a phlebotome in shape. It is most likely, therefore, that the Greeks and Romans used a knife of this shape also. A passage in Rufus of Ephesus shows that in his time the lithotomy knife had the handle shaped like a hook to extract the stone after the perineal incision was made: Καὶ εἰ μὲν πρόχειρος εἴη, τῇ λαβῇ τοῦ μαχαιρίου ἐκβάλλειν, πεπιεσμένον δὲ τῇ λαβῇ τραχείᾳ τε καὶ καμπύλῃ ἐξ ἄκρου, ὡς ἂν μάλιστα συμφέροι τῷ ἔργῳ. 'And if it (the stone) be at hand we must eject it with the handle of the knife, made with the handle roughened and curved at the tip, as best suited for the operation' (ed. cit. p. 52). One of the knives in the scalpel box shown in Pl. IV has the handle of this curved shape. Although Celsus gives us no information about the shape of the ordinary lithotomy knife, he goes on to describe in detail a special variety of lithotomy knife invented by Meges, a surgeon of whom he had a very high opinion. As this passage has given rise to much discussion I shall quote Celsus's description in full: Multi hic quoque scalpello usi sunt. Meges (quoniam is infirmior est potestque in aliquam prominentiam incidere, incisoque super illam corpore qua cavum subest, non secare sed relinquere quod iterum incidi necesse sit) ferramentum fecit rectum, in summa parte labrosum, in ima semicirculatum acutumque. Id receptum inter duos digitos, indicem ac medium, super pollice imposito, sic deprimebat ut simul cum carne si quid ex calculo prominebat incideret, quo consequabatur ut semel quantum satis esset aperiret (VII. xxvi).