RDF Metaphors

Sorry I haven't been in touch for a while; it's been completely hectic, but I promise to make more of an effort in the future.

There still seems to be a widespread misunderstanding regarding the differences between XML and RDF - importantly, this misunderstanding is often at the decision making level.  I thought that some real-world metaphors would help exemplify the differences.  However, from the ones I quickly came up with, I think I was wrong...

• In Good Will Hunting, if XML is Matt Damon (lost and without meaning), then RDF is Robin Williams, giving him direction.
• XML is a black and white photograph, RDF gives it colour.
• Similarly, if XML is the standard twelve notes of western music, then RDF provides the scales.
• Similarly (again...), if XML is the a-z characters and punctuation marks, then RDF provides the grammar for constructing meaningful sentences.

What I was trying to say is that XML means nothing.  Point a computer at some arbitrary XML, and it won't be able to tell you anything about what that data means.  It's the same as pointing it at a tab separated list of values - what can you deduce from the stucture?  Nothing.

Point a computer at arbitrary RDF (which will probably be represented in XML) though, and the computer will at least be able to break the data down into a series of statements, gaining at least a set of basic statements and relationships for whatever is being described.

If anyone has a better metaphor for RDF, please let me know...