The students are wisely trying to find a way to break up a big, abstract goal into smaller, more concrete subgoals. This is the right idea. But in this case the numbers are just too big. And “acreage” is not necessarily the best way to think. There are 1,500-acre plots of land that are more environmentally precious than other 90,000-acre plots. Thinking about “acreage per year” is akin to a museum curator thinking about “canvases per year,” without regard to period, style, or painter.

TNC named the oak savanna the Mount Hamilton Wilderness (based on its highest peak, the site of a local observatory). Identifying the area as a coherent landscape and naming it put it on the map for local groups and policymakers. Before, Sweeney says, Silicon Valley groups wanted to protect important areas close to their homes, but they didn’t know where to start. “If you say, ‘There’s a really important area to the east of Silicon Valley,’ it’s just not exciting, because it’s not tangible. But when you say, ‘The Mount Hamilton Wilderness,’ their interest perks up.

This is not a story about land; it’s a story about abstraction. TNC avoided the trap of abstraction—saving 2 million acres per year—by converting abstract blobs on a map into tangible landscapes. TNC realized, wisely, that the context had grown more ambiguous, and the solutions had grown more ambiguous, but that their messages could not be allowed to grow more ambiguous. Concreteness is an indispensable component of sticky ideas.

We frequently learn how to solve problems by tackling them. The National Park Service, US Department of the Interior, has learned to protect America’s natural environment in the hundred years since it was established. One of the responsibilities of the service is forest management. We might agree, roughly, on the meaning of the objective of good forest management. That objective needs to be translated into intermediate goals necessary for the achievement of that high-level objective. A good forest is beautiful and accessible, and it has healthy trees.

One desirable intermediate state that contributes to these goals and objectives is the absence of destructive fires. From the early twentieth century, the policy of the NPS was one of zero tolerance. Every outbreak of fire, however small, would be extinguished— the basic-level action. But the incidence of fire did not fall: it increased.

Computer simulation of fire control policies suggests the explanation. Most forest fires are small and burn themselves out. In doing so, they remove combustible undergrowth, and create firebreaks that limit the spread of future fires. So the best way to reduce fire is not to extinguish all fires. The Service adopted a different view of the goals that would achieve its higher level objective: controlled burning replaced zero tolerance. But what actions does this goal require? In 1972 the Service decreed a new policy: it would put out man-made fires but allow natural ones to burn.

Sixteen years later, the largest fire in American history swept through Yellowstone National Park. In extremely dry conditions, several fires joined together. Lightning was probably the original cause, though perhaps some fires were deliberately lit by arsonists. By the time the blaze was controlled by a force of 25,000 fire-fighters at a cost of over $100 million, almost half the vegetation of the park had been destroyed. Today’s guidelines allow experienced forest rangers to use their judgement in deciding which fires should be tackled and which left to burn. Experience has shown that too much effort devoted to fire extinction is counter-productive. But some fire-control activity is essential. Time demonstrates, but only slowly, whether policy has gone too far in one direction or the other— whether actions are appropriate to states, whether goals are appropriate to objectives.

A very powerful resource position produces profit without great effort, and it is human nature that the easy life breeds laxity. It is also human nature to associate current profit with recent actions, even though it should be evident that current plenty is the harvest of planting seasons long past.