Originally, the atoms of carbon from which we're made were floating in the air, part of a carbon dioxide molecule. The only way to recruit these carbon atoms for the molecules necessary to support life-the carbohydrates, amino acids, proteins, and lipids-is by means of photosynthesis. Using sunlight as a catalyst the green cells of plants combine carbon atoms taken from the air with water and elements drawn from the soil to form the simple organic compounds that stand at the base of every food chain. It is more than a figure of speech to say that plants create life out of thin air.

Very simply, we subsidize high-fructose corn syrup in this country, but not carrots. While the surgeon general is raising alarms over the epidemic of obesity, the president is signing farm bills designed to keep the river of cheap corn flowing, guaranteeing that the cheapest calories in the supermarket will continue to be the unhealthiest.

Eat mostly plants, especially leaves.

One surprise is how deeply the food system is implicated in climate change. I don't think that has really been on people's radar until very recently. 25 to 33 percent of climate change gases can be traced to the food system. I was also surprised that those diseases that we take for granted as what will kill us - heart disease, cancer, diabetes - were virtually unknown 150 years ago, before we began eating this way.

...forgetting is vastly underrated as a mental operation.

For is there any practice less selfish, any labor less alienated, any time less wasted, than preparing something delicious and nourishing for people you love?

A vegan in a Hummer has a lighter carbon footprint than a beef eater in a Prius.