What does the title imply "we are our own metaphor"?

The arrangement of molecules within the 3 phases of matter are shown in the picture. 

for the solid, the molecules are packed closely together. they don't have much space to move, so they just practically vibrate. for the liquid, the molecules are relatively farther from each other. the liquid molecules can flow freely but not as much as the gases. in the gases, the molecules are very far from each other. they are very sensitive to slight changes of pressure, volume and temperature.