The literature on what to eat and not to eat, what to do and not to do, on medicines that convert human stomachs into drug-stores, is simply boundless. If we believe all we read, we must consider the location we are in before we can safely draw the breath of life; we must not cool our parched throats without the certificate of the microscope. We must not eat without an ultimate analysis of each item of the bill of fare, as we would take an account of stock before ordering fresh goods; and this without ever knowing how much lime we need for the bones, iron for the blood, phosphorus for the brain, or nitrogen for the muscles. In short, there is death in the air we breathe, death in the food we eat, death in the water we drink, until, verily, we seem to walk our ways of life in the very valley and shadow of death, ever subject to the attack of hobgoblins of disease.