Interaction with other people is the key part of our society. We need to be able to smile and say hello to all we meet, make small talk with our neighbours, teachers and peers.

"The great secret Eliza, is not having bad manners or good manners, or any other particular sort of manners, but having the same manner for all human souls: in short, behaving as if you were in Heaven, where there are no third-class carriages, and one soul is as good as another."
-- George Bernard Shaw