Quattrocento (kwa-tro-CHEN-to) is Italian for 400, and is used to indicate the 1400s-the period of the Renaissance. The Renaissance (1300s-1600) was a movement across western Europe that embraced a new appreciation for the art and literature of ancient Rome and Greece. It produced some of the greatest art in the history of the world-a "rebirth." Italy was the center of the Renaissance.

Renaissance painters were interested in working in a naturalistic style. In order to do this, a technique called "perspective" was needed, to help the artist represent the world in a more realistic way. Perspective is a system for representing three-dimensional space on a flat surface. It is based on the optical illusion that parallel lines appear to meet in the distance.

Architect/writer Leon Battista Alberti (1404-1472) invented a device to aid in this technique. He built a wood frame, then stretched transparent material over it, which he divided into squares with thread. He looked through this "window" at the subject he was going to draw. Onto a piece of paper or canvas with a corresponding grid penciled in, he sketched his subject as it appeared in each little square, thus accurately copying it to scale.