The Devil's Dictionary: Lock-and-key (n.)

The distinguishing device of civilization and enlightenment.

[The Peril notes that it is hard to have a high opinion of any place -- Houston, for example -- where, unlike the small town of his youth, it is necessary to have a working lock on the back door of one's home, which feature was absent from the young Peril's own home until he was at least fifteen or sixteen years old, even though he grew up on the main street in his home town.]