Nothing is ever lost by courtesy. It is the cheapest of pleasures, costs nothing, and conveys much.Erastus Wiman
Manners are a way of showing other people we care about them.Adam
(Brendan Fraser's character in Blast from the Past)
Do unto others as you would have them do unto you.Golden Rule
Don't do to others what you don't want them to do to you.Silver Rule
Any way you look at it, treating people is a good idea. All people--all shapes, sizes, colors, abilities, religions, orientation, gender--like to be treated well.