Yahweh said to Joshua, This day have I rolled away the reproach of Egypt from off you. Therefore the name of that place was called Gilgal, to this day.
"Flint knives [cf. Exodus 4:25] are sharpened by chipping away at the edge of the stone, so that clean, sterile stone is exposed, since bacteria and viruses cannot grow in rock. Circumcision was thus performed with an instrument possessing comparable sterility to today’s surgical scalpels. In view of the likelihood of infection following this operation with a contaminated instrument, use of the flint knife was enormously beneficial and therefore commanded by the Ultimate Healer (or in this case the preventer). [Note: Jay D. Fawver and R. Larry Overstreet, "Moses and Preventive Medicine," Bibliotheca Sacra 147:587 (July-September):277.] 