All my jokes are stolen, is that art theft too

If it is, I'm in a lot of trouble

I'm a cultural robin hood, I steal from the witty and give to the dull

oops, did it again.
How about I start giving credits

That was from a movie staring Walter Matthau and Glenda Jackson from around 1978 or 1980.
I just did the research in google and I'm pretty sure I got the line written down almost verbatim, but it did not appear on the first page as being from either of the 2 movies they made together in those years, House Calls or Hopscotch, that's how insignificant my stolen line is.
But if I'm right, that's very close to 40 years I've remember that line, so I'm at least going to give myself some credit for that

As far as more mainstream art is concerned, I can also a remember another line that I saw written many years ago.
" we have invented nothing"
It was uttered by someone called Pablo Picasso as he was being lead out of a cave at Chauvet in France, where he had just been allowed the rare privilege of viewing 30,000 year old cave paintings.