On the solar system’s schedule of arrivals and departures, spring always rolls in right on time in the maturity of March, conveyed precisely to its eternally recurring equinox by the clockwork of physics. Real spring — that is, the spring we feel and experience as sentient beings living on earth — comes and goes in a more haphazard way, following a timetable of random weather patterns perceived and parsed by our human emotional responses to change. Spring, as we know it, is a caprice — a sudden and unaccountable change of mood and orientation.
First, it is an April thing. The “spring” of March in the latitudes of New England is all mockery and broken promises seasoned with snow squalls. Here, the vernal equinox is conceptual, not consequential.
My earliest introduction to cause and effect was put this way: April showers bring May flowers. But between the showers and the flowers, spring arises ephemerally, carrying our mood aloft right along with it.
It is a heady sensation that arrives invisibly when the afternoon sun breaks through the fleeing clouds of a morning-long rain. What is that smell? It is so elemental, so of the earth, in the sense of both dirt and planet. And because it is a smell and not a sight or sound, it transports us in a way other sensations do not, thanks to the way our brains are constructed.
The olfactory bulb, which processes smells, runs along the bottom of the brain and has direct connections to the amygdala and hippocampus, two potent seats of emotion and memory. Our other senses bypass the area. In 2004, research by neuroscientists at Brown University showed a correlation between the activation of these brain structures and the emotional intensity of memories, which is why inhaling the earthy smell after a spring rain brings back such potent youthful memories of playing in cold muddy brooks or digging up earthworms for the first days of fishing season.
But what is that smell?
It actually has a name: petrichor. The word, linguistically derived from stone (petra) and blood of the gods (ichor), was coined back in 1964 by a couple of Australian scientists, who wrote in the British journal Nature that the aroma arises when oils that build up on some plants in dry periods are released into the air by rain, combining there with geosmin, a chemical produced by bacteria (actinomycetes) in the soil that is released, again by the rain, and disseminated by spores in the air.
If at the end of a spring day, you do smell like dirt, as Margaret Atwood advises, you have perfumed yourself with geosmin. Incidentally, the chemical is also responsible for the earthy taste of beets. Parfumiers use it to impart depth and mystery to their fragrances. Apparently, even the ineffable can be bought and sold. Geosmin is available online for $40 a gram.
But it is much easier and cheaper just to go outside in this potent time between showers and flowers and turn over the earth in your vegetable gardens and flower beds with spades and trowels. You may start the chore with a head full of random thoughts and distractions. But in time, your exertions will, breath by breath, infuse your sensibilities with the essence of spring and memories of idylls long ago.
Sure, it may be just a trick of chemistry and neurobiology, but its ability to transport weary souls from the leaden lassitude of winter’s forced March to the golden promises of April and May is pure alchemy.