Trade isn't about goods. Trade is about information. Goods sit in the warehouse until information moves them.
C. J. Cherryh
Culture is how biology responds and makes its living conditions better.
C. J. Cherryh
The warrior may fight for gold or for an immediate gain, or for something to take home for the winter to feed the family. The soldier is part of a more complex society. He's fighting for a group ethic of some sort.