At the beginning of Proust’s monumental work, In Search of Lost Time, there is an episode where a single bite of a madeleine dipped in tea triggers a flood of memories. This moment, often referred to as the “Proustian effect,” is familiar even to those who haven’t read the book, as it vividly illustrates how scent can evoke memories. In this way, scent doesn’t just linger at the tip of our noses before disappearing—it is closely tied to human memory, and it does this in the blink of an eye. A scent can easily and swiftly retrieve fragments of memories buried deep in our brains, even those we didn’t consciously try to remember from long ago, perhaps from childhood. We often struggle to recall what a friend told us just yesterday—but scent has a stronger pull. And it doesn’t stop at simply reminding us of a specific moment or scene from the past. It also conjures up the emotions and intangible feelings that were tied to that time.

This experience is entirely personal. When I smell frankincense, I’m reminded of entering a cathedral in Europe. I can feel my heart race once again, just like on that day, as I stood in awe, listening to the majestic sound of the Mass echoing through the grand, towering Gothic architecture. If I catch the scent of birch or juniper, I’m taken back to summer camping trips, watching the campfire my dad built flicker in the dark. I remember the anticipation as we waited for the sweet potatoes to cook, the warmth of sitting around the fire, and the joy of sharing stories with my family. This is how I relive the feelings and atmosphere of those moments through scent. However, someone else might smell birch and be reminded of the devastating aftermath of a fire, or catch a whiff of juniper and recall a crisp morning in the forest. The reason people perceive and distinguish scents differently is because their experiences—their memories—are different. (This ties back to what I discussed before.)

However, while these phenomena occur, the way various organs in the human body operate remains the same for everyone. Most senses, such as sight and hearing, are processed through the thalamus before being transmitted to the cerebral cortex, where they are perceived as “sensations.” But smell is different. When a scent binds to the olfactory receptors, it immediately generates an electrical signal that travels directly to the olfactory bulb, like an express delivery straight from the source. This direct path allows the scent to reach the amygdala and hippocampus—parts of the brain responsible for emotion and episodic memory—without delay. This is why smell is often considered the most primitive or “first” sense. While the emotional memories evoked by scent are often seen as romantic, in reality, this is a natural and scientific process.

Additionally, scent travels through the limbic system to reach the hypothalamus and pituitary gland, which regulate the autonomic nervous system, immunity, and hormones. Using this scientific basis, aromatherapists have conducted various clinical experiments to demonstrate that plant fragrances can influence human emotions and stimulate the autonomic nervous system, leading to physical reactions. In particular, several studies have focused on the connection between smell and memory, noting that one of the early symptoms of Alzheimer’s disease—a difficult-to-treat illness—is the loss of smell. Currently, in countries like the United States and Japan, olfactory testing kits are being used to help detect Alzheimer’s early, and recently, news has surfaced about the development of olfactory kits in Korea, using scents that are culturally familiar. The idea that scent can not only evoke personal memories but also aid in the research and treatment of diseases is gaining traction.

The ability to recall the past, whether through good memories or bad, is a remarkable aspect of being human. The fact that this ability can be enhanced through the sense of smell means that scent is not merely something fleeting or intangible, confined to the realm of personal taste. Instead, it allows us to bring vitality to life through a more active sensory experience. A fragrance can help instantly transform stress-filled emotions into feelings of calm, turn a melancholic mood into memories of happier times, or shift lethargy into a moment of focused energy. Working with scent is like traveling through time, delicately managing emotions with a sensory skill that is both intricate and complex.