Judging from the flash bulbs continually snapping around the Yard, one might guess that the most distinctive features of the Harvard landscape were an infamous bronze toe and an army of friendly squirrels. Less excitable residents might point elsewhere: to venerable architecture in the form of slate-roofed, red-brick first-year houses, antique classrooms, wide stone archways, marble staircases, heavy doors, high windows and ubiquitous commemorative plaques. Others might cite the iron fence circling the Yard and its largely closed gates, inviting the rest of the world to look but not touch.

But what is, in fact, properly characteristic of a University? What in our landscape necessarily indicates the status of these grounds as a place of thought, reflection, Socratic dialogue and fantastic rhetoric?

Naturalists might look to the river. The Charles, like the Cam, the Tiber and the Tigris before it, carries a hefty symbolic weight (along with a number of dirty secrets). Its banks provide ample ground for strolling, musing, jogging and Pointillist flights of fancy; its water gives necessary distance from the quotidian city. And its lovely bridges pay homage to generations of Harvard successes.

A more practical contingent might point to the venerable personalities saturating these few square kilometers. The hallmark of a great university, the argument goes, lies in its ability to convene and to remain the site of discussion; this University should thus be a place of many discussions, potential or actual. (This argument is best set within the usual pseudoscientific rhetoric of success, brainwaves and pouvoir.)

But I would argue differently. Certainly, buildings, rivers, bridges and personalities greatly enhance the University's reputation and experience: they give it space, boundary, voice. Without any of them, our campus might be unrecognizable. Still, something inestimable is missing: Trees. Lots (in the crying sense) of them.

Consider for a moment the spreading oaks of the Yard, the carefully ringed elms of House courtyards, the pale beeches lining Memorial Drive. Something in the planned arboreal abundance ties this physical piece of Cambridge together into something more than historic buildings or great minds: a university.

It is precisely these trees which delineate our land, space and buildings in an academic way. I mean this, with all due respect, in the least green way possible. The allusion is historical: ever since Plato --for the modern West, ever since Milton immortalized Plato's "groves of academe" in "Paradise Regained"--it has been clear that every self-respecting university needs a small forest.

This, of course, is no light heritage. The Greek site, Academe, was an Athenian public garden where philosophers met their students to discuss among the olive trees. Had he felt the symbolic weight of the future academic world on his shoulders, Plato could hardly have chosen a better spot. Among trees, Nature is in its element; the connection is to a world innocent of human sullying, whose rules are loftier and more immediate than those of cities.