Source is xkcd 979: Wisdom of the Ancients.

http://www.explainxkcd.com/wiki/index.php/979:_Wisdom_of_the_Ancients

Haha:

The title is a satirical reference to the notion that the "ancients," i.e. from thousands of years ago, possessed knowledge that has been lost to the centuries (such as exactly how Stongehenge was built), and that artifacts from those times do not fully divulge such knowledge. The fact that the "ancient" referred to in the comic is from 2003 (only 8 years before the comic was published) is an exaggeration of the feeling that the forum poster is lost to the sands of time, but in some sense this feeling is nonetheless true, since Cueball is unlikely to be able to contact him.

I think it also goes with music like this:

That's good but I like their song NARA better:

The only thing worse, would be:  you are the one that posted the question in 2003!