TITLE: What is the source of this E̶r̶d̶ő̶s̶ quote?
QUESTION [14 upvotes]: Namely, the following one

"All problems appeared once in the [American Mathematical] Monthly."

I remember reading it several years ago... When I first posed the question, I believed that I had read it somewhere in Krantz' Mathematical Apocrypha but according to Carlo Beenakker the quote is nowhere to be found in the said recollection of stories and anecdotes of Krantz. I gather that Erdős might have expressed it in relation with the history of what is nowadays known as the Sylvester-Gallai theorem but it'd be perfectly possible for me to be wrong in this respect too.
I thank you in advance for your replies.

REPLY [22 votes]: In Index to Mathematical Problems, 1980-1984 - Page xi by Stanley Rabinowitz this quote is attributed to Léo Sauvé:

Léo Sauvé, former editor of Crux Mathematicorum, an international problems journal, once quipped that it seemed like all problems "had once been published in the Monthly"