I received help from a doctor named "Gary" in another forum. He said that Zyban was a already well-known anti-depressant drug.
Someone did reasearch at LLU on using it to help depressed smokers quit. Nicotine, apparently, is the strongest anti-depressant that there is. If it is substituted with the non-addictive Zyban, the underlying depression is treated and the need to get Nicotine from smoking is lessened.
Well, this is my "telephone" answer. For a direct explaination, go to the "Right Arm of the Message" section of TRO.
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As the Happy Moments Roll,
Pastor Andrew