From a speech he gave at the Web 2.0 con­fer­ence in April 2008: Clay Shirky tracks the his­tory of our cog­ni­tive sur­plus, explain­ing what we could, or need to do with it:

So how big is that sur­plus? If you take Wikipedia as a kind of unit, all of Wikipedia, the whole project—every page, every edit, every line of code, in every lan­guage Wikipedia exists in—that rep­re­sents some­thing like the cumu­la­tion of 98 mil­lion hours of human thought. […]

And tele­vi­sion watch­ing? Two hun­dred bil­lion hours, in the U.S. alone, every year. Put another way, now that we have a unit, that’s 2,000 Wikipedia projects a year spent watch­ing tele­vi­sion. Or put still another way, in the U.S., we spend 98 mil­lion hours every week­end, just watch­ing the ads. This is a pretty big sur­plus. Peo­ple ask­ing, “Where do they find the time?” when they’re look­ing at things like Wikipedia don’t under­stand how tiny that entire project is, as a carve-out of the cog­ni­tive sur­plus that’s finally being dragged into what Tim O’Reilly calls an archi­tec­ture of par­tic­i­pa­tion.