Mat 12:33 Either make the tree good, and its fruit good; or else make the tree corrupt, and its fruit corrupt: for the tree is known by [its] fruit.
One of my favorite verses in the Gospel both because it is such a useful idea (that the means determine the ends) and because, in the Greek, it combines both the moral lesson that we normally here with a lesson in economics.
"Make" is from the Greek word, poieô, which means has two meanings, "to make" and "to do." In the sense of "make," which is how it is used here, it means "to produce," "to create," and "to cause." It has an economic sense of producing something through work.
"Good" is kalos, which means "beautiful," "honorable," "noble," and "of fine quality."
"Fruit" is karpos, which means both the fruit of trees and the fruit of your actions. In the later sense, it means "return" or "profit." The play on words here is clear: produce a good tree and you also produce good profits.
"Corrupt" is sapros, which means "rotten," "putrid," and "diseased." Again, this word has a moral sense and an economic sense. It is used to mean "worn out" and "stale," that is, not retaining any value. It is also used as a metaphor for "unsound" and "bad."
"Known" is from ginôsko, which means "to learn to know," "to recognize," and "to learn."
The principle here of "good producing good" is used as a tool for judgment. Those who claim to have good intentions and high ideals, but who do not accomplish good and productive work (or good and productive societies) are not good. The quality of people (or trees) is never judged by their intentions, their logic, or their bloodlines but by the quality of what they produce. This is a powerful and important lesson for all those that follow "idealistic" and "fair" systems that never seem to do anything but produce misery for their followers.
How do you choose what philosophy to follow? Look first at what it has produced? Are people who follow that philosophy happier, healthier, and more successful? Or at they more miserable, less healthy, and less successful?