GIVEN THAT TOBACCO is a legal substance that generates enormous wealth for governments throughout the world, the substance is not likely to be banned, says Dr. Henningfield. But if tobacco were declared an illicit drug, there is abundant historical evidence that people would risk their lives to obtain it. For example, in the Middle East during the 17th century, people had their hands and heads chopped off for smoking forbidden tobacco, which did not prevent their fellow countrymen from risking life and limb to secure the substance.

A few decades earlier, when tobacco was introduced to England, it became worth its weight in silver. King James I then banned the cultivation of tobacco in England so that he could exercise complete control over its price. ''Seeing that people would pay almost any price for tobacco,'' says Dr. Henningfield, ''monopolies were started so that governments could benefit from the desires of their people. Taxes were implemented, and governments became dependent on revenue generated from nicotine addiction.''

This economic dependence seems to be yet another factor contributing to the power of nicotine. In what might be called a nationwide experiment in the sociology of smoking behavior, many local governments have waged public health campaigns against smoking and instituted legislation that restricts or bans smoking in public. The results are encouraging: less than 30 percent of all American adults smoke cigarettes, compared to 40 percent 20 years ago. While half the world's population still smokes, the United States is the first country to see a decrease in tobacco use. KICKING THE HABBIT A number of programs, many of them free, are available to the smoker who wants to quit. The following use a combination of behavior modification and group-support techniques. The American Cancer Society's FreshStart Program consists of four free group-counseling sessions, led by former smokers, to help participants analyze why they smoke and how to stop. Included are strategies for dealing with two of the biggest obstacles to quitting permanently - stress and weight gain. Contact your local chapter of the American Cancer Society; in New York, at 19 West 56th Street (586-8700). For those who want to quit on their own, ''FreshStart: 21 Days to Stop Smoking'' is available on audio- and videocassette at many bookstores. The audiocassette can also be purchased through the mail for $9.95 (order number 61783-4) from the audio division of Simon & Schuster, 1230 Avenue of the Americas, New York, N.Y. 10020. The video ($29.95) can be ordered by calling 800-445-3800. The New York Lung Association's Kick-the-Habit Program devotes the first three of its six free 90-minute sessions to helping people figure out why they smoke and the rest to support after quitting. The association also publishes a manual, ''Freedom From Smoking,'' available with a $7 contribution, and a video, ''In Control,'' for $59.95. Contact the New York Lung Association, 22 East 40th Street, New York, N.Y. 10016 (889-3370), or your local affiliate of the American Lung Association. The Seventh-day Adventists' Breathe-Free Plan to Stop Smoking consists of five days of instruction and support-group activities, and at least one follow-up session. Participants are encouraged to give up caffeine and alcohol, at least for the duration of the program, because they often trigger the desire for a cigarette. The course and activities are free, although a small donation for materials is requested.

Contact the Adventist Information Center, 12 West 40th Street, New York, N.Y. 10018 (382-2939 or 800-832-2210). Smokenders offers a six-session course that teaches participants how to withdraw gradually from cigarettes. During the first four sessions, people are allowed to smoke, but are restricted to certain times and places. The program, offered at several locations, costs $295. Call 800-243-5614. The LifeSign Smoking Cessation Program is offered with eight individual therapy sessions at the American Health Foundation. Each participant is given a pocket-sized computer that beeps when smoking is permitted. The beeps occur at gradually increased intervals, ceasing entirely in two to four weeks. The foundation's program normally costs $400, but when it is taken as part of a research project, there is no fee, except for a $100 deposit for materials (and motivation) that is refunded after completion. Contact the American Health Foundation, 320 East 43d Street, New York, N.Y. 10017 (953-1900). Smokers can purchase the LifeSign computer with an instruction booklet for $73.95 by contacting Health Innovations, 13873 Park Center Road, Suite 336, Herndon, Va. 22071 (800-543-3744).