In his 1838 poem A Psalm of Life, Henry Wadsworth Longfellow (once America's most popular poet, now an item on every high school's forced-feeding menu), wrote
We can make our lives sublime,
And, departing, leave behind us
Footprints on the sands of time
Yeah, well, maybe... But what is certain is that we're all leaving behind some pretty big footprints ecologically-speaking. And since it's Earth Day, it's a good time to measure your feet. The helpful folks at the Earth Day Network and Redefining Progress have an online calculator
that estimates your ecological footprint. Just plug in your data, and you'll get, borrowing another line from Longfellow, the "mournful numbers". Happy Earth Day.