In the markets of ancient Chu, a merchant held up a spear and declared:

"This spear can pierce everything."

Then he held up a shield and declared:

"This shield can block everything."

A voice from the crowd asked the question that would echo through two thousand years of philosophy:

WHAT HAPPENS WHEN YOUR SPEAR STRIKES YOUR SHIELD?

The merchant had no answer. The paradox — 矛盾 — became the word for contradiction itself.