Abstract I SUPPOSE it is a fitting sign of the times that chaos has become, simultaneously, an important concept in science, the title of a widely read book, and a topic for cocktail party conversation. It is to the last of these subjects that this essay is addressed. The English word “chaos” comes to us from the ancient Greek x<iocr. The earliest extant reference is from Hesiod, who lived in the eighth and seventh centuries B.C. In his Theogony (lines 114- 116), he wrote: Thus, Chaos was the name of the most ancient of the Greek deities, the first member of the Pantheon. From very early times there was apparently an association between the first god, Chaos, and the unformed matter of the universe, chaos. The word “chaos” is first recorded in English in Scala perfeccionis by Walter Hylton in 1440. He writes of chaos as “a thycke derkeness.”