Frost, Fall, and Photons

“Nature’s first green is gold,” writes Robert Frost in “Nothing Gold Can Stay,” admiring in tandem the beauty and the transience of changing autumn leaves, “her hardest hue to hold.”

Few poets wrote more eloquently about New England fall than Robert Frost. His most famous poem, “The Road Not Taken,” nestles the speaker’s introspection into a “yellow wood,” amid the pensiveness of the fall foliage. And not to mention his ode “October,” which sings the season’s praises: “O hushed October morning mild [...] Retard the sun with gentle mist; / Enchant the land with amethyst.”

Indeed, the “amethyst” and “gold” of a Harvard fall is an experience like no other. Frost’s ideas capture it seamlessly: the wind that stirs the branches of the yellow and red trees outside your window, the seeds and leaves that tumble onto your shoulders as you hustle across the Yard, the evenings when the sun stretches and shimmers across the Charles River. Fall settles into Harvard just as we settle into the rhythm of our classes, somewhere just before the first midterm week, when we’ve both revived our relationships with old friends and maybe broached nascent connections with new ones. It catches us at a moment when we’ve embraced the new year of classes and all it has to throw at us, but also when we can turn around and smile at our past selves too.

So autumn, as Frost’s poems all agree, is a time for reflection, a vantage point from which we consider the roads we’ve taken. And never has that been the case more than this year, when the vast majority of us will not be on campus in the coming months. Even those of us still in the Northern Hemisphere, like myself, recognize a dissonance between this coming season and our usual Harvard fall. Fall encompasses more than a set of seasonal changes; it’s the contented relief of returning to a place and to people we know and love, set against the cool breeze and changing leaves. And without those social cues, whether we’re in Boston or Beijing, Maryland or Melbourne, we feel disconnected from the course of our seasons and of our lives. How can we be expected to have a fall semester without, well, a fall?

It appears that this coming fall, then, is one of loss, of feeling cut off from the place that brings us so much fulfillment, of being cast far away. And, when you look at the science of the season, that actually makes us not too dissimilar from those yellow and red leaves dotting the Yard; just as we’re experiencing this sense of loss and exile, those leaves have also been stripped from their verdant past, the source of their vitality.

Leaves begin as nothing more than the energy-gathering appendages of a deciduous tree, through which the plant metabolizes the sun’s energy in photosynthesis. In high summer, leaves absorb the energy from sunlight to allow the tree to prosper and flourish green. That’s because during the first set of photosynthesis reactions, the energy from sunlight strikes the electrons in each plant cell’s chlorophyll molecules, causing them to leap between molecules and through the rest of the photosynthesis chain. But not all the sun’s light energy gets used in these reactions; only longer wavelength photons (light molecules) on the red end of the visible light spectrum and shorter wavelength photons on the blue end power photosynthesis. The photons that vibrate a little more frequently bounce off of the leaves instead, where our eyes perceive them to have the complementary color to red: green.

But around September or October, the days get shorter, the nights get longer. There simply isn’t enough sunlight to justify the tree’s expending energy to undergo photosynthesis. As a result, the tree forms a thick, cork-like barrier between the branch and the leaves, which both protects the branch’s vulnerable future state and cuts the leaf off from receiving nutrients from the heart of the tree. Effectively choked, the leaves cannot renew the chlorophyll they need to maintain photosynthesis, and other, weaker pigment molecules reveal themselves. Carotenoids reflect the yellow-orange hues, and anthocyanins the reddish-pink. Though these pigments, too, break down without sunlight, eventually leaving only the glum brown tannins in the cell membranes to tint the leaves as they fall from the branches above.

Thus fall, in all respects, is a season of loss and mourning for our arboreal friends. One that I’m sure we all sympathize with from our little corners of the world, as this so-called fall semester commences. But the question I ask myself is why, if fall brings so much loss to the plant life, do we find so much continual wonder and enlightenment in its beauty? Frost’s autumnal poems use the wide world around us to draw lessons for each of our own little worlds; they teach us the value that reflection plays in our perpetually-moving lives. At Harvard, fall doesn’t make us hopelessly sad, it allows us the opportunity to view the past and the future in close contrast — to feel that strange mixture of appreciation and disappointment, hope and regret through which we find gratitude for the life and community we have.

So maybe, though we find ourselves scattered among the grasses and a deep sense of loss, we can try to afford our coming semesters the same bittersweet regard we do the fall foliage. What we have lost, whether it be summer skies or the vibrancy of a dining-hall dinner, reminds us painfully of what we love. There is no better time to pause, give a gentle sigh, and be thankful.

Tessa K.J. Haining ’23 lives in Adams House. Her column appears on alternate Fridays.