[Illbay]

Well, I haven't seen a barrel of oil--and neither have you.

A "barrel of oil" is simply a unit of measure. This is like saying "I've never seen an ounce of gold."

People buy and sell gold by the ounce all the time, and never actually, physically possess any of it.

This guy's been studying with Bill Clinton.

[RightWhale]

I see. It's like I've never seen 3-D space. In fact, I've never seen a dimension at all. I'm making a list of things I have actually seen, but so far the paper is blank. This could be useful.