[s7e4] The Year Of The Slow Invasion -

"The Power of Three" isn’t about the cubes; it’s about the Doctor realizing that his time with Amy and Rory is finite. It captures the bittersweet nature of being a companion: you can’t run forever, and sometimes the most important things happen while you’re just sitting around waiting.

People use them as paperweights, doorstops, and ornaments. [S7E4] The Year Of The Slow Invasion

The Doctor essentially "restarts" the hearts of everyone affected in seconds. Final Thoughts "The Power of Three" isn’t about the cubes;