Economics is the study of how societies use scarce resources to produce valuable goods and services and distribute them among different individuals. If we think about the definitions, we find two key ideas that run through all of economics:

La verdadera literatura no tiene fronteras, trasciende idiomas y culturas.

Never be satisfied with where you are; always strive for better.

The greatest threat to our forests isn’t logging—it’s indifference.

To live under the American Constitution is the greatest political privilege that was ever accorded to the human race.

数学是一门活生生的学科，随着新思想的出现而不断发展。