One hot summer day when we were just kids, my older brother offered me a sip from a bottle of soda he was drinking. “It’s something new,” he said, ” You’ll like it.”

The bottle, with its cheery orange label, certainly looked harmless enough. How bad could it be?

If you’ve ever unwittingly taken a big gulp of Moxie, you already know the answer.

The word “disgusting” leaps to mind, along with a few others including “bitter” and that old standby “medicinal.”

Had he refilled an empty pop bottle with diluted cough syrup? Was this a practical joke? I wouldn’t have been surprised if a bunch of kids had leapt from behind a nearby bush, pointing and laughing hysterically.

My brother just shrugged and took another long pull, flashing an enigmatic smile I’ve come to recognize as a common expression among aficionados of this particular product: a subtle, self satisfied quasi-smirk which conveys the unspoken message, “You, my friend, are unable to appreciate the finer things in life.”

Thus was I introduced to Moxie, the unique beverage, which, since May 10, 2005, has been canonized as Maine’s official soft drink.

Moxie historians report that sometime in the mid-1870s, one Dr. Augustin Thompson, a native of Union, Maine working in Lowell, Mass., created the formula for a new patent medicine.

Christening his elixir “Moxie Nerve Food,” the good doctor insisted it would provide quick, effective relief from a long list of maladies including insomnia, irritability, paralysis and “softening of the brain.” Frankly, I can’t help wondering whether that last ailment may actually have inspired some folks to purchase Moxie in the first place.

A few years later, carbonated water was added to the recipe and Moxie the soft drink was born.

The precise origins of its unusual name remain murky. Some maintain that it’s derived from a language once spoken by one of Maine’s indigenous Native American tribes. Others trace its roots to an actual root found only in some remote corner of a tropical rain forest.

Whatever its etymology, the word soon entered American vernacular and “moxie” is now listed in dictionaries as a synonym for “force of character, determination or nerve.”

Celebrity endorsements from sports figures like Ted Williams and “Babe” Ruth sparked a sales boom and Moxie became a nationwide hit. That’s right. Believe it or not, for a time, in the early 20thcentury Moxie was the best-selling soft drink in America.

At the very least that’s a testament to the power of advertising; but what about the product itself? Have you ever actually tasted it?

Fortunately my job at CBS News gave me a chance to explore what has always been a baffling mystery: the true source of Moxie’s continuing popularity.

And, what better place to start exploring than The Annual Moxie Days celebration in Lisbon Falls? This lively summer gathering attracts hardcore Moxie fans from around the globe. One year a septuagenarian Moxie-phile from Scotland won the prize for the longest distance traveled to attend the event.

Moxie Days features countless examples of Moxie memorabilia including one of the original Moxie Cars. These clever mobile billboards sported a realistic life sized artificial horse bolted to an automobile chassis. Sitting astride this “horse,” the driver maneuvered the vehicle by means of a massive steering wheel sprouting from the animal’s neck.

Examine a Moxie Car up close and you’ll no doubt wonder whether the designer was spiking his Moxie with something just a wee bit stronger during the critical development phase.

Quirky memorabilia aside, but still no closer to unraveling the secret of Moxie’s popularity, I appealed to The Moxie Man himself: Mr. Frank Annescetti.

Standing behind the counter of his Moxie Store in Lisbon Falls surrounded by Moxie memorabilia, Frank finally gave me the plausible solution I’d been seeking.

“You see,” he explained, "when you take your first sip of Moxie it doesn’t taste very good.” I’m with you so far Frank. “But,” he continued, “you take another sip and it still tastes kind of bitter. After your first bottle you aren’t sure you like it. But, you try another bottle, then another....”

As I’m listening to The Moxie Man, light dawns and the truth hits me like a tsunami of bitter cola. Of course!

A Moxie drinker never does actually like the taste of Moxie. That’s not even the point! The point is to endure it!

Which also explains why the word moxie, meaning “force of character, determination, nerve,” continues to resonate so deeply with Mainers.

Glancing at Frank’s “Moxie Makes Mainers Mighty” T-shirt I finally realize why that slogan is true. A person has to be mighty tough just to drink the stuff!