I have expected my children to have good manners since they were old enough to demand something and worked bloody hard at instigating it. A biscuit was not given up until a grunt that sounded something like "Ta" or "Pees" had been uttered, no matter how much of a tantrum ensued and I always made sure that appropriate manners were used by everyone around them to set a good example. Good manners are now second nature to my children - they say "please" and "thank you" without a second thought, they open doors for people and they stand aside to let people pass. I have had strangers comment on this, saying "Oh you're ever so lucky. My child is rude and ungrateful." It is hard not to reply with a comment about parenting techniques but I've always accepted the compliment graciously, with a smile and a nod and an inner self-appreciating smirk.
Our children are forever being berated by older generations for being disrespectful or for going off the rails but when my 10 year old has held a door open for a member of the public and s/he swishes past without a second glance, I have to admit that I have called out a sarcastic "Thank you" to the departing body or, if we are still in the same vicinity, I have pointed out their rudeness.
I read somewhere that the original quote (in the title) now has a double meaning - the original meaning is that "manners are the basis of our society" and now that has been extended to "manners are created by our society". I'm inclined to agree. We need to nurture something to be proud of... you reap what you sow.