The echo of having been there embossed into a surface.

A distinctive design that is usually rectangular and used as a symbol, a signaling device, or a decoration.

Footprints are the impressions or images left behind by a person walking or running. Hoofprints and pawprints are those left by animals with hooves or paws rather than feet, while "shoeprints" is the specific term for prints made by shoes. They may either be indentations in the ground or something placed onto the surface that was stuck to the bottom of the foot. A "trackway" is set of footprints in soft earth left by a life-form; animal tracks are the footprints, hoofprints, or pawprints of an animal.[from wikipedia]

Those who came to see the torch, found it missing

The concept, signs, and slogans

In Chinese philosophy, yin and yang (also, yin-yang or yin yang) describes how apparently opposite or contrary forces are actually complementary, interconnected, and interdependent in the natural world, and how they give rise to each other as they interrelate to one another.