How can one define the great social forces of our time?

Here's a remarkable quote, it struck a chord within me - my individual efforts, when added to the good will and good work of others, have the capacity to be part of something great!

Great social forces are the mere accumulation of individual actions. Let the future say of our generation that we sent forth mighty currents of hope, and that we worked together to heal the world.

- Jeffrey Sachs
The End of Poverty