“It is seldom that any of our bad habits or flaws disappear by a mere nature process of natural extinction. At least it is very seldom it is done by the instrumentality of reasoning or by the force of mental determination. What can not be destroyed however may be dispossessed. One case may be made to give away to another and to lose its power entirely has the reigning affect of the
mind. Here’s an example: A youth may cease to idolize sensual pleasure but it is because of the idol of wealth. The desire to make money has gotten ascendancy, so he becomes disciplined. But the love of money might have ceased to be in his heart if he was draw to ideology and politics. Now he is lorded over by the love of power and moral superiority instead of wealth. But there is not one of these transformations in which the heart is left without an object. The human heart’s desire for one particular object is conquered. But its desire to have some object of adoration is unconquerable. The only way to dispossess the heart of all its affection is by the explosive power of a new one. Thus is it not enough to hold out to the world the mirror of its own imperfections, it is not enough to come forth with the demonstration . . . of the character of their enjoyment, it is not enough to just simply speak the conscience, to speak its follies. Rather, you must seek, as a preacher, every legitimate method of finding access to the heart for the love of Him who is greater than the world.”
~ Thomas Chalmers, as quoted by Tim Keller in Gospel-centered Ministry.
The complete text of "The Expulsive Power of a New Affection" by Thomas Chalmers, 1780-1847, can be found here.