For the past five years, Bill and Melinda Gates have published an annual letter, modeled on Warren Buffett’s legendary Berkshire Hathawayshareholder missives, which help set the global philanthropic agenda. This year, they’ve taken a different tack: rather than list their foundation’s wins, losses and priorities, the letter, released today, takes the form of a manifesto. Actually, an anti-manifesto. And in dissecting its details with Bill Gatesyesterday – “the exercise of writing forces you to have logic and critical reasoning,” he acknowledges, sporting sharp new black-framed eyeglasses – you get a surprisingly clear window into how the planet’s richest person and biggest philanthropist plans to spend the rest of his life.

Rather than posit on what’s required to end extreme global poverty – the primary goal of the Gates Foundation – this year’s letter focuses on three myths that impede progress. Specifically, that poor countries are doomed to stay poor, that foreign aid is a waste of money and that saving Third World lives just creates more starving mouths to feed. As statistics obliterate the fallacies of all three – Matthew Herper thoroughly debunked the Malthusian worries in Forbes two years ago — the Gates’ (Bill takes on the first two, Melinda the third) make short work of these arguments.

For me, the three myths prove less telling about Bill and Melinda Gates than three other threads that cut across the letter.

First, that for all the cash and brainpower, they can only succeed if governments buy-in (or at least don’t sabotage progress). The foreign aid example is obvious, and the recent U.S. budget compromise actually increases spending on polio eradication by $50 million (the Gates Foundation still doubles what the U.S. government provides). Gates points out that, since he has the “capitalistic freedom” to allocate his resources as he chooses, his foundation serves a de facto due diligence that this is money well-spent.

But at a point not too far in the future, “you’ll almost have to give a reason why a country is a poor,” says Gates. And that reason, perhaps save a few geographically-cursed countries in land-locked Africa, will be government policies. Those that offer market-based incentives and invest in health and education, says Gates, will almost surely pull themselves up, if they haven’t already. It’s why China has so thoroughly outperformed its fellow population behemoth, India. The poor souls trapped in North Korea? Gates offers no promises.

Second, you get a sense of optimism. For all of Gates’ data-laden wonk-speech, he’s one of humanity’s biggest cheerleaders. “There are no headlines, ‘Oh my God, look at what’s happened over 25 years of progress,’” he says, adding “the change since I was born to now is very dramatic.”

And he’s now making a prediction: There will be almost no more poor countries by 2035. The “developing world,” to a large degree, will no longer exist. Two years ago, Gates funded the Commission on Investing in Health, led by Larry Summers and 25 global experts in various disciplines, which envisioned a convergence of advances that will allow almost every country on the planet to see their children live past five years old at a rate equal or better than the U.S. standard in 1980 – a bellwether stat for Gates that indicates “health equity.”

That 2035 date also coincides with the year Bill Gates turns 80, a fact not lost on him. It’s the third underlying message of the letter: a personal blueprint for the next two decades. “It’s easier to think about years where you expect to be around,” Gates says. “It’s kind of nice, people can either tell me, ‘Well you really messed that up’ or ‘You got that right.’” For a human atlas, who can reel off the health care policy differences between Vietnam over Nigeria, or the checklist needed to bring up Haiti, the 2035 health equity goal provides “a finite problem” to solve.

It also matches the way he and Melinda have built the Gates Foundation, which will wind down, deploying all its resources on their stated goals – health equity currently sits at number one — within 20 years of their passing. “Rich people in those times will be able to pick what the problems are then,” says Gates. His work, however, will be done. It starts again today.

Also on Forbes: