Everything is a function of time.
We have infinite potential, but finite lives. No matter how hard we work, there'll always be important projects left unfinished.
As of writing, we can't manufacture time. But we have a close proxy: health.
Given this, you might say that medicine is about buying people more life. Extending the quantity, and improving the quality, of their lives.
This seems reasonable. But it requires another, very important assumption.