There is no wealth as great as knowledge, and there is no poverty as destitute as ignorance. What interests me is not money, not fame, not physical goods, but ideas and their relation to the future of humankind. The greatest thing that distinguishes us from animals is our propensity for thinking about the distant future, the distant past, and planning. No other animal plans twenty years in advance. But seldom do people think about what the world will be like in a thousand years, or a million years, or a billion years. The earth is 4.5 billion years old, but it will be at least 5 billion years until the Sun's luminosity increases enough to boil the oceans as it becomes a red giant. Barring any orbital decay that moves earth out of the habitable zone, or another mars-size impact, or a Venus-like runaway greenhouse effect, or a nuclear holocaust, life on earth will survive until then. The first animals evolved approximately 600 million years ago. The first animals were wormlike creatures in a Precambrian sea. If there is still civilization on Earth in one billion years, it may be as different from us as we are from worms. It may, qualitatively, be to us what we are to worms. It may be our direct descendants or the descendants of some other species. This is a humbling thought. But first we must evade looming environmental catastrophe. Economics is fundamental within human society, and part of an important interdisciplinary understanding that must be cultivated to enable democratic action to delay the death of our precious civilization. The only reason free oxygen exists on earth is because of billions of years of photosynthesis that has bound up carbon below. But now our “invisible hand” is on a mission to extract every bit of oil and coal that can be produced for less than the market price of each, no matter what pristine habitat may be thereby damaged. A high fossil fuel tax is needed to internalize the negative externalities of fossil fuel use.