The Incas of ancient Peru possessed no writing. Instead, they developed a unique system expressed on spatial arrays of colored knotted cords called quipus to record and transmit information throughout their vast empire. The present book is based on a firsthand study of actual quipus that survived the destruction of the Inca civilization. Written by a mathematician and an anthropologist, this book acquaints the reader with the cultural context of the quipus, the problem of interpreting arti...