|If Keats doesn't think this is a bird,|
I'd like to know exactly what he
thinks a bird is.
But apostrophe is not limited to Wild Bill and poets who go around talking to nightingales and using words like "wert." You can hear apostrophes made all the time, the man who addresses his insensate car on a cold morning when the battery is weak and the engine is weakly growling and sputtering, "C'mon, c'mon, start!" The commuter who curses at the driver who just cut him off changing lanes. "You %@#!!" Is it apostrophe when people talk to their pets? Usually no, we have a reasonable expectation that Rover understands when we say, "Come!" or "Bad boy!" even if he doesn't respond. Once, however, I overheard a woman rebuking her dog, "No barking? Now what have I said about this?" Now that's apostrophe.
How apostrophe came to be a punctuation symbol, I honestly cannot discover. The comes from a Greek root apostrophos, "to turn away." (Perhaps the punctuation is so named because of its curved, "turning away," shape?) (Parenthetically, an apostrophe does not have to address an absent or insentient being, any "turning away" from the stream of discourse, as in a digression, is also an apostrophe. This includes parenthetic remarks such as this one.)