Here's a question: How did the expression nine days' wonder (or nine day wonder, as it is also known) come to refer to someone or something that creates a short-lived sensation? According to one source, the answer lies in an old (and no longer common) proverb: a wonder lasts nine days, and then the puppy's eyes are open. That proverb alludes to the fact that a puppy, like a kitten, is born blind; after nine days or so, its eyes open and what was once marvelous is for the first time clearly seen.
The phrase nine days' wonder first appeared in print in the late 1500s, and an allusion to it can be found in this Shakespearean exchange from Henry VI: King Edward observes You'd think it strange if I should marry her... to which the Duke of Gloucester agrees That would be ten days' wonder, at the least and the Duke of Clarence adds That's a day longer than a wonder lasts.

So when is a nine days' wonder also a flash in the pan? When the short-lived sensation is initially viewed as promising and then ends up being disappointing or worthless. That figurative meaning has its origin in a literal flash in the pan: that is, the firing of the priming (or explosive) in the pan (or hollow) of a flintlock musket without discharging the piece.

Ok, now here's my question. The same day I read the post above, I was reading a book that had a reference to a "seven day's wonder." What's that?! Is it different than a "nine day's wonder"?

I've heard of the "9", but never a "7" so now I'm confused!

Sure it's different Linda you just have to wonder two days less is all.

Do you feel like you just got short changed?