Yin and yang
Yin and yang was a symbol of Chinese origin.

In 2000, a sign in the window of Alexandria Books had a yin and yang symbol on it. ()

The patch of the US 5th Armored Infantry unit was a blue and grey Yin and Yang. ()

A Yin and yang was among the imagery from different Earth faiths found in the White Church, a shrine to a religion on Terralysium. ()

In 2377, a hologram of Reginald Barclay described the injection of synthetic antigens into the crew of  and modifications to the starship's shields in relation to one another, calling the former "the medicinal ying to the shield's yang." The Doctor then inquired, "And what if the yang doesn't work?", which "Barclay" then assured him wouldn't occur. ()

External link 
 
Symbols