Fiddling Around

I don't know about everyone else but sometimes my mental conversations come to a screeching halt when I come to something I hadn't thought much of before...of course by now many of you may have noticed that about me. The mental brakes came on recently over the phrase "fit as a fiddle". Once you hear the origin it seems obvious though it had never occurred to me until I read it.
The phrase "fit as a fiddle" has been around for a long time,dating back to the 1600s,quite simply it compares one's health to that of the instrument (fiddle) of being able to perform better when in tune and good repair. The word fit has changed in meaning somewhat since the phrase originated in that today it is used more in describing healthy and energetic,where as in the 1600s it was used more to mean something suitable. Seems like an interesting twist to me,but I'm easily amused!