For the children of Israel walked forty years in the wilderness, until all the nation, even the men of war who came forth out of Egypt, were consumed, because they didn't listen to the voice of Yahweh: to whom Yahweh swore that he wouldn't let them see the land which Yahweh swore to their fathers that he would give us, a land flowing with milk and honey.
"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.] 