Trina Auslander, age 15, of DeKalb, I11., for her question:

 WHEN WAS THE "AGE OF REASON"?

A period of great intellectual activity that started in the 1500s and lasted until the late 1700s is called the Age of Reason. During this period, scientists believed that through reasoning and experimentation they could discover the laws by which nature operates.

The ideas expressed during the Age of Reason led to the development of the modern scientific method and created a scientific revolution.

To carry out experiments, scientists needed new tools. Inventors met these needs with such instruments as the microscope, sextant, slide rule and chronometer. Aided by the new instruments, scientists advanced rapidly.

During the Age of Reason Sir Isaac Newton revolutionized ideas about astronomy, Robert Boyle, Antoine LaVoisier and Joseph Priestly founded modern chemistry, Rene Descartes invented analytic geometry and William Harvey discovered how blood circulates in the human body.

Philosophers such as Thomas Hobbes and John Locke began to urge the development of a social science and joining from the United States with such men as Benjamin Franklin and Thomas Jefferson.