In the introduction to Magic Squares and Cubes, W.S. Andrews wrote writes, "The study of magic squares probably dates back to prehistoric times. Examples have been found in Chinese literature written about A. D. 1125 which were evidently copied from still older documents. It is recorded that as early as the ninth century magic squares were used by Arabian astrologers in their calculations of horoscopes, etc. Hence, the probable origin of the term magic, which has survived to the present day." He added that "a magic square consists of a series of numbers so arranged in a square that the sum of each row and column and of both the corner diagonals shall be the same amount which may be termed the summation.