In its second-quarter earnings report Wednesday, Facebook revealed that, on mobile, its business is healthier and stronger than anyone could have predicted.The social network said that it made 41 percent of its $1.6 billion second-quarter advertising revenue, or roughly $656 million, from mobile. Heading into the report, even the most bullish of analysts were only predicting that mobile would account for a third of advertising revenue. Most were about $200 million off the mark.How did Facebook manufacture such a surprising feat on mobile? Just like some relationships on Facebook: it’s complicated.Part of the surprise can be attributed to Facebook’s continued desire to hold its future financials close to the vest and not, like other public companies, share guidance ahead of the time. And Facebook’s mobile business, just one year old, is far more mysterious than its desktop or payments business.The unsexy reality, though, is that the company was able to do what it has been talking about all along: connect the dots between its improved mobile apps, targeting technology and mobile ad units. Listen to any of the company’s earnings call and you’ve heard this we’re-getting-better story over and over again. Apparently everybody just tuned out those parts -- or more likely got lost in the skepticism of the market that was weighing down Facebook’s stock.When asked for clarity on why mobile ad revenue was so strong this quarter, Facebook executives provided a variety of answers with one underlying theme: demand is insanely high.CEO Mark Zuckerberg said that Facebook’s investment in building better apps was starting to pay off. COO Sheryl Sandberg talked about mobile app install ads as being a totally new, Facebook-owned market that was picking up steam. Even CFO David Ebersman weighed in with some insight.