a
reference to a belief that the cure or answer to a
malady is to apply a small amount of the thing that caused the
problem,
sickness, etc. For
example, some may think the best cure for a
hangover is
having another of the same drink in the morning. This comes from an ancient belief that if one was bitten by a
dog the best antidote was placing a hair (or even burnt hair) of that same
dog on the wound.