"I walked with my friend to a newsstand the other night, and he bought a paper, thanking the newsie politely.  The newsie didn't even acknowledge it. 

'A sullen fellow, isn't he?" I commented.

'Oh, he's that way every night,' shrugged my friend.

'Then why do you continue to be so polite to him?" I asked.

'Why not?' inquired my friend.  "Why should I let him decide how I'm going to act?"