Step 1: Understanding the context.
In the extract, the poet reflects on how the Earth can teach us about life. The idea is that even when everything appears dead or lifeless, something remains alive beneath the surface, such as the potential for renewal in nature.
Step 2: The answer.
What remains alive is the life force or the underlying potential for growth that is often hidden during harsh or barren times. It refers to the cycles of life and nature that always contain the possibility of revival, even after apparent death.
Final Answer: \[ \boxed{\text{What remains alive is the potential for life, growth, and renewal, hidden beneath the surface.}} \]