Daniel Aaron's poems include a series he called "Biographia Literaria," caustic little portraits of American writers he had read or taught. A short epigram on Thoreau, in its final form, reads:
Talker, gressorial,
Range extra-terrestrial.
The two lines capture some key features of Thoreau's work. Thoreau was a talker, to be sure, as any undergraduate can attest who struggled to get to the end of Walden. And he was a walker, an activity he celebrated in one of his best-known essays, "Walking" (which had begun as a lecture, an act of talking). For Thoreau, walking was not a means of getting to a destination, but "sauntering," a verb alluding to a ruse used by vagabonds in the Middle Ages: they would claim to be going to "Sainte-Terre," the Holy Land, and beg for money to help them get there. Except that they had no intention of doing so.
But Thoreau's saunterer does get there. Thoreau's "Holy Land" is not aplace but a state of being, achievable to those who take their walking seriously. For every walk can be a pilgrimage. If we are true walkers, as we still feel the earth under our feet, we're in fact already beyond it. But Dan's epigram really exists only for one purpose–to allow him to use the adjective "gressorial," an ornithological term referring "to the feet of birds which have three toes forward, two of which are connected, and one behind" (Oxford English Dictionary). Dan's lifelong love of lexicographical arcana here also led him to capture a central fact about Thoreau.
A passionate bird-watcher, Thoreau was himself a bit of a strange bird in his hometown of Concord, Massachusetts, a place where eccentrics were not in short supply. But this is not all the adjective accomplishes. It turns out that Thoreau, too, sometimes thought he was a bird, and not in a metaphorical way. "I am no more lonely than the loon in the pond that laughs so loud," he exclaimed in Walden. Conveniently, "gressorial" and "extra-territorial" rhyme, thus mapping the trajectory of the talker-walker's journey as it is envisioned in these two lines: from, at one end, the earthbound realm ("gressorial"), where the likes of us saunter only awkwardly, like four-toed herons, to, at the other end, the heavenward where our minds might take us ("extraterrestrial"). And there, humans transformed into birds, we may gambol like the merlin whose aerial gyrations Thoreau watched with the greatest pleasure: "It appeared to have no companion in the universe--sporting there alone--and to need none but the morning and the ether with which it played." Dan's epigram thus contains a lecture's worth of insights on Thoreau, but it does so casually and with just the right degree of irony.

