“Not nice!” said our eldest.
“What?” asked my wife.
“It isn’t nice to spit,” said our eldest.
“That’s true,” supported my wife, “but the thing I just read means something different from that. The phrase ‘spitting image’ means that someone looks just like someone else.”
“Oh,” said our eldest. “Okay.”
Here’s what I found.
While some people think that “spitting image” is a deviation from “split image” or “spirit and image” or something like that, all evidence points to a salivary origin. In fact, the older mentions of the phrase use “spit and image” instead of “spitting.”
The idea behind the phrase is that a person is so like another that the original “spit” the copy out of their mouth. According to phrases.org.uk, examples of likeness and being spit out of someone’s mouth date back to at least the 17th century. To back up the fact that the “spit” in question is definitely of the salivary type, the same phrase with the same meaning is attested in both French and Norwegian (though the Norwegians suggest that a person is not spit out of the mouth, but blown out of the nose).
I still can’t say that I completely understand the phrase, since I’ve never looked at something I’ve spit out and thought that it bore a striking resemblance to myself. Other people may think that I look like a bit of phlegm, but I’ve never thought it personally. Oh well, I guess I’d rather have a truth that I don’t fully understand than a lie (like “split image” or “spirit and image”) that makes complete sense.
So next time someone asks you where we got “spitting image” from, you can spit some truth at them.