[TOMT] A quote about fantasy being like a soup, from which everyone takes and gives

I read once, regarding (I think) the non-controversy about whether "Harry Potter" was a copy of "The books of magic" by Neil Gaiman, a quote (probably by Gaiman himself) in which fantasy was compared to something like a "boiling pot of soup, from which sometimes you take a bit and sometimes you add something new", but I can't find it anywhere.

I can't remember the actual quote, but the image stuck with me somehow. Does anyone remember the actual quote?