Ever felt helpless in the face of the world's big problems? Maybe you're thinking too big. Try a single-minded focus on a single societal ill, and you may find - as these do-gooders did - that one person can change the world.
"If we only had more people who cared, we could end injustice and achieve world peace," jokes Dave Purchase. "At least that's what I believed in college." Purchase, 64, is a person who cares - he started the nation's first public needle-exchange program to keep drug users from contracting and spreading AIDS. He is seasoned enough, however, to laugh about those old notions. "Now I just want to get drug users access to sterile needles. I'll worry about injustice and peace on the weekend."

In the face of really big problems - providing health services to the poor, improving a country's educational system, preserving the planet's biological diversity - most of us feel impotent. Yet the following four people - social worker Dave Purchase, civic volunteer Margie Kerr, teacher Betsy Rogers, and ethnobotanist Mark Plotkin - illustrate the power of individual lives. These four remind us that we can instigate change, can make a difference.

Our power comes from letting go of the whole and targeting the one - one person single-mindedly attacking one task can significantly affect one problem. One contribution may seem insignificant, but Purchase was on target in believing that we simply need people who care. If we each committed ourselves to leaving this world better than we found it and if we each devoted the hammer of our actions to one nail, collectively the cathedral of our efforts would be truly staggering.