Jessica Chung, age 16, of Henderson, Nev., for her question:

WHAT WAS ARISTOTLE'S GREATEST CONTRIBUTION?

Aristotle was one of the greatest and most influential thinkers in Western culture. The Greek philosopher, educator and scientist lived 300 years before the time of Christ.

Aristotle's greatest contribution was that he influenced a great deal of human knowledge. Today, many of his ideas have been absorbed into the language of science and philosophy.

Long after his death, Aristotle enjoyed tremendous prestige. Leading Christian and Arab scholars of the Middle Ages said his writings seemed to contain the sum total of human knowledge. St. Thomas Aquinas, one of the most influential philosophers of the Middle Ages, called Aristotle the "master of those who know."

Aristotle was the most scholarly and learned of the classical or ancient Greek philosophers: He familiarized himself with the entire development of Greek thought preceding him. In his own writings, he considered, summarized, criticized and further developed all the rich intellectual tradition he had inherited.

Aristotle's treatises make up nearly all of his surviving writings. They were probably written for use either as lecture notes or as textbooks at the Lyceum, a school Aristotle founded in Athens in about 334 B.C.

Aristotle's works on logic are collectively called the Organon, which means instrument, because they investigate thought, which is the instrument of knowledge. Aristotle was the first philosopher to analyze the process whereby certain propositions can be logically inferred to be true from the fact that certain other propositions are true.

For Aristotle, the most striking aspect of nature was change. He argued that to understand change, a distinction must be made between the form and matter of a thing.

In his metaphysics, Aristotle tried to develop a science of things that never change and investigated the most general and basic principles of reality and knowledge.

For Aristotle, ethics and politics both concerned practical knowledge, that is, knowledge that enables man to act properly and live happily. He argued that man's goal is happiness and that he achieves happiness when he fulfills his function.

Aristotle also said that it was necessary to determine what man's function in life is.

When Aristotle was about 18 years old, he entered Plato's school in Athens, Greece. The school was called the Academy, and Aristotle remained there for 20 years.

Plato recognized Aristotle as the Academy's brightest and most learned student and called him the "intelligence of the school" and the "reader."