[balti]

This relationship between him and the natural world around him—this sense of synchrony—lay at the heart of his daily, monthly, yearly monitoring of the changing seasons. In 1851, he began to compile long lists of leafing-out and flowering times. As summer came, Thoreau wrote that he now thought of the journal as “a book of the seasons.” The full implications of this were gradually revealed to him. “For the first time,” he wrote on April 18, 1852, “I perceive this spring that the year is a circle.” This might not sound very revelatory to us today, and of course painters and poets had for centuries depicted the seasons, portraying wild autumn storms and lush spring meadows. But Thoreau’s tracking of cyclical change was a radically different endeavor, and the beginning of a truly ecological understanding of the natural world, years before the term ecology was coined in 1866, by the German scientist Ernst Haeckel (another admirer of Humboldt’s ideas).

“Make a chart of our life, know how its shores trend, that butterflies reappear and when—know why just this circle of creatures completes the world,” Thoreau noted in 1852. Over time, nature’s interrelationships and the planet’s regenerative power emerged for him. The seasons became a metaphor of Earth as a living organism, a planet thumping with life—even in the darkest depth of winter: “There is nothing inorganic,” he wrote; “this earth is not, then, a mere fragment of dead history … but living poetry like the leaves of a tree—not a fossil earth—but a living specimen.”


Thoreau the observer was also a passionate participant, and his cyclical attunement comes across vividly in two beautifully illustrated books, Thoreau’s Animals and Thoreau’s Wildflowers, containing journal extracts selected by the writer Geoff Wisner. Thoreau’s own yearning for rebirth was clear as he listened to a red-winged blackbird “calling the river to life and tempting ice to melt and trickle like its own sprayey notes. Another flies over on high—with a tschuck and at length a clear whistle. The birds anticipate the spring—they come to melt the ice with their songs.”

Always alert to the bonds that connected each individual plant, bird, and frog to the greater cosmos, he was stirred by the sound of the first bullfrog in May—the sign for him that summer had finally arrived: “I hear in his tone the rumors of summer heat. By this note he summons the season … it reminds me at once of tepid waters—and of bathing. His trump is to the ear what the yellow lily or spatterdock is to the eye.”