Life keeps on changing. We have new inventions, new ways of working, and new leisure activities. We also face new problems, including political crises, threats to our security, and environmental catastrophes. But which changes really make the biggest difference? Universal education, electricity, going to the Moon, new philosophies, or random changes to the natural environment? What makes a change have high impact? Can we predict what will change our world in the next few decades? Will it ever be possible for us just to stay the same as we are? And would we ever want to stay the same?