The river had flowed for thousands of years. Its current was strong and proud, its banks clean, and many animals made their homes close to its verdant shores. Since time immemorial, this river had been a source of life here, and the river was proud. It viewed the animals sipping from its waters with munificence, feeling its place affirmed in the grand scheme of life.
One day, Man came to the river armed with plans and drawings, and measuring equipment. Then came the machinery, and the noise, and before the river knew it, a bridge had been built over its mighty span.
“How dare you!” cried the river. “I have always been here, providing for my flock, giving the gift of life to the flora and fauna that have teemed on my shores! How can you think of dismissing my power thus!”
The bridge did not respond, because it was made of metal and stone, and thus could not hear. It merely ignored the river, and stood in stony silence. Metally silence, too.
The river grew angry, and plotted its revenge. It was patient: it had been here for thousands of years. Slowly, slowly, slowly, by eroding the banks and the foundation of rock upon which it rested, the river ate away at the bridge’s support. A thousandth of a millimeter, year after year. Unfortunately the river came from a pretty constant source, and the rainfall in these parts was not particularly great, so it could not create giant waves to destroy the bridge in one crashing metaphorically-representative swoop. But it kept eating away, year after year.
The bridge remained silent, year after year.
Then one day, the foundation finally became too weak to support the bridge, and it gave way. The bridge came crashing down into the river in a mess of twisted metal, shards of broken stone, snapped cables.
“Ha HAH!” cried the river. “I have finally defeated you, along with foolish Man who tried to contain my mighty span!”
Unfortunately, Man had already defeated itself thousands of years prior, in a nuclear conflagration that had killed everybody off. Not only that, but the war had destroyed most animal life and vegetation, so the banks of the river were empty and fallow, and the surface of the river was covered in slime and shiny oily residue.
The river was once more content, even though it now had bits of bridge sticking out of it.