A nail is driven out by another nail. Habit is overcome by habit.
|in Habit Quotes by Desiderius Erasmus|
Bad company is like a nail driven into a post, which, after the first and second blow, may be drawn out with little difficulty; but being once driven up to the head, the pincers cannot take hold to draw it out, but which can only be done by the destruction of the wood. - Saint Aurelius Augustine