"Since no two people on this planet of more than 4 billion look exactly alike, you might think that there must be millions of ways in which faces differ from one another. Not so, Pentland says. Faces actually vary according to a mere 100 factors....Yet the computer must understand what these 100 factors are. Pentland fosters such understanding through the use of a technique whereby each face image is deconstructed into separate eigenfaces, a word derived from the German prefix eigen, meaning 'own' or 'individual.' "
—Evan I. Schwartz, "A face of one's own," Discover