The Internet is an Ocean of Unsourced Quotations

Today I was asked for the source of 

That which is so universal as Death, must be a blessing.

Several sites claimed Friedrich Schiller said it (replacing "blessing" with "benefit'), and maybe he did say something like that in German.  I did a lot of searches in various places just using "universal as death."  It turns out Jonathan Swift said something similar: "It is impossible that any thing so natural, so necessary, and so universal as death, should ever have been designed by Providence as an evil to mankind."

• Thoughts on Religion (1765), published posthumously

In 1765 Schiller was only 6 years old. Even if he read Swift and came up with a shorter version, Swift had the idea first! See: https://en.wikiquote.org/wiki/Talk:Friedrich_Schiller

The Woodlawn Cemetary in Palm Beach, FL has 

"That which is so universal as Death, must be a blessing" inscribed on its gate, and as of 2006 the inscription was unsourced

http://historicpalmbeach.blog.palmbeachpost.com/2006/02/01/inscriptions-origin-still-a-mystery/

Attribution Can Be Hell (or The Web of Deceit)

Simplicity is the ultimate sophistication.

Some months ago we got an attribution question from a Professor who wanted to use the quotation above in an article or book (I can't remember which).  The internet attributes it to Leonardo da Vinci; but the internet does not give a citation.  So I looked in every quotation book and every online quotation thing, but it's not there.  I did a JSTOR search in art history titles.  No results. Then I did Google Books searches and found Leonardo's notebooks and Thoughts on Art and Life (translated into English).  But I couldn't find anything like it in there.  Finally I asked an art librarian who asked a friend of hers who is a Leonardo da Vinci scholar.  The scholar had never heard that quotation.

Widespread quotation misinformation predates the internet.  William Safire got himself embroiled in just such a scandal.  He had used a quotation attributed to Edmund Burke in a column, and then a reader wrote him a letter asking when and where Burke had said said quotation.  Safire checked his copy of Bartlett's Familiar Quotations, 14th edition, which placed the quotation in a certain letter.  Safire sent a reply.  The guy wrote back: he'd examined that letter, and the quotation wasn't in it.  So then Safire embarked on a fruitless quest to prove that Burke really wrote, " The only thing necessary for the triumph of evil is that good men do nothing."*
The 16th edition of Bartlett's lists this under Burke as "Attributed."

Now it is possible that Leo from Vinci said something that could be translated as the above quotation and that somebody found it somewhere written down by Leo on some forgotten manuscript in a hidden archive.  So if you are that somebody, I wish you would identify yourself and cough up a citation.

It is also possible that some person has, through error or evil design, perpetrated a web-lie.  If you are that person, please fess up.  And tell the world who really said "Simplicity is the ultimate sophistication."

* William Safire On Language, NY: Times Books, 1980, pp 224-227.

UPDATE 11/08/11 I find a reference to this problem in Wikiquote.
ANOTHER UPDATE 4/3/15 Quote Investigator did a thorough investigation!