Telling us we’re in a recession is like telling us the sky is blue. Our reaction is a collective yawn, followed by the sound millions of people changing channels (or Web sites) at once.

I mean, come on. Things have been going south for a while now. Tell us something we didn’t know.

Instead, the announcement of a recession by the National Bureau of Economic Research was predictable at best. The only surprise is that the recession began way back in December 2007.

So I guess it was only fitting that I stumbled upon a “Planet Money” podcast that tried to answer a question that’s on the minds of a surprising number of people lately:

Just what the heck is money, anyway?

It sounds like a stupid question, but think about it: There’s more going on here than bringing home a paycheck and paying the bills. What, exactly, does “money” mean?

In the podcast, The Ascent of Money author Niall Ferguson takes a stab by defining “money.” His answer: Money is a relationship, based on trust, between lenders and borrowers. Lenders give money to borrowers with the understanding — the trust — that the borrower will pay off the debt. And that makes sense. Almost all of the “money” that we spend these days is invisible. We simply trust it will be there when we need it. When that trust breaks down, bad things happen.

Believe me, the discussion is a lot more interesting than that. Listen to the podcast in its entirety, then tell us: How long will this recession last? When will that monetary trust return?