While buying some cologne for her mother, a friend of mine related that she had very nearly concluded the purchase when she revealed in conversation to the salesclerk that her mother was in the hospital. It seemed the mother had a very serious illness, but was expected to make a complete recovery. The daughter thought that a gift of her favorite scent would cheer her up more than the traditional flowers or balloons.

"You shouldn't buy her favorite cologne," she was told sternly by the clerk. "She'll associate it the rest of her life with being sick. You'll ruin it for her forever."

Was the clerk right? That's hard to say, but prevailing wisdom is that we do tend to make strong and possibly illogical associations between smells and what's going on around us at the time, particularly if we're going through something emotional.

If you're around 50 years old, a whiff of Youth Dew or Heaven Scent will send you right back to high school.

Men or women who wear a strong and consistent fragrance get associated with that scent. Many of us remember a grandmother who wore a citrus cologne or a school teacher who wore some floral fragrance. A friend of mine loves the smell of Angel by Thierry Mugler because it "smells like my girlfriend." Here the transfer is complete: his girlfriend does not wear the scent nor does she smell like Angel because she wears it. Instead, Angel smells like her.

Why are we so quick to associate smells with times, places, and people but not visual stimuli (like colors) or sounds or even flavors?

Despite the fact that human beings have always had noses and an active olfactory life, we know surprisingly little about the world of smells. We don't even understand physiologically how smelling is even possible. (There are two theories circulating but no one knows definitively.) What we do know is that the human nose can differentiate about 10,000 different scents and that the portion of the brain that processes smelly information is very close to the long-term memory section of the brain.

However, brain activity is far too complex for such a simple approach (smell and memory are near each other in the brain, so they're near each other in our thoughts). But it is true that we have a very powerful ability to keep scents in memory.

Musician Garth Brooks once said that catching a sudden, unexpected whiff of a particular perfume was all that it took for him to be emotionally transported back to a different time and place in his life. We all experience that. It's peculiar because there is no conscious memory of the scent. The scent suddenly invades our nostrils and a whole avalanche of memories tumble out: old friends, a past time in life, situations, emotional states.

Scent is perhaps the "wildest" of our human senses. We don't truly understand it. Animals use it to hunt and to recognize friend, foe, and potential mates. Humans mostly ignore it or bottle it as an artifice.

But just as a whiff of a predator can send an animal into a panic, scents have powerful primordial connections in our brains as well.

Perfumistas are people who are inordinately involved and attracted to fragrances. Most of them will tell you that the joy of perfume is not something logical. It defies explanation, yet it is strong and vibrant. Fragrance gets tied up with emotions in our heads: we feel emotional release with one scent, fond but gentle memories with another, and maybe a sense of haunting or regret with a third.

Should you buy a sick person her favorite perfume? Let's say your best friend gets fired. If you got her some perfume to cheer her up, would that be a good idea, or would it just taint that scent forever after as the smell of getting fired? Can a man ever find pleasure again in the perfume of his ex-wife?

Surprisingly, my own experience tells me that it is not so much the actual experience that colors our fragrance association, it is the state of mind we're in as we experience it. It's almost like perfume can "freeze frame" an emotional snapshot of us at a given moment and store it into our memory.

A hospitalized person who feels grateful and happy and well on the road to recovery can easily manage to use her old favorite scent and not damage her olfactory memory bank. A friend who gets fired but uses the event to change her life for the better may be inspired by the perfume that she used at that time. It may be used later in life as a confidence-builder. Likewise, a man may well remember the last woman in his life who wore a particular scent but if he is not bitter or angry about the break-up, he may come away with a sincere appreciation or fondness for the scent.

Scents happen. People who love perfume should keep using and cherishing the fragrances they like, and just let life fill in the gaps in the way that it wants. Now it so happens that a once-beloved scent can be ruined for us by sheer circumstance, but then again, it is not unusual for a mediocre scent to rise wildly in our esteem when colored by pleasant associations.