One example is Numbers chapter 19, which describes those who touch a dead body as unclean, and imposes a ritual washing process. Believe it or not, until the mid-1800s, physicians not only ignored this concept, but they frequently went from autopsying dead bodies to operating on the living without washing their hands! Once this changed, of course, hospital mortality rates dropped considerably. Further, the materials described in Numbers 19 include ingredients like hyssop, which is a natural anti-bacterial, wool ash, which is gritty, and cedar, an irritant that would encourage repetitive rinsing. Go into hospitals today, and you'll see doctors washing with gritty, antibacterial soap and lots of water.
