How important is the Atomic Theory?

Suppose something terrible were to happen to Earth, and we the living could only pass one sentence to the next generation. What would it be? Nobel Prize winning physicist Richard Feynman in his book, Six Easy Pieces, nominates the first sentence of this paragraph.

All things are made of atoms. They are the little particles that move around in perpetual motion, attracting each other when they are a little distance apart, but repelling upon being squeezed into one another.

The concept of atoms is that important.