The only known form of pre-Columbian "writing" in South America is the Incan quipu. Incan clerks, known as quipucamayo, were trained to record and translate these quipus as "memoranda or registers made from strands of cord, in which different knots and colors signify different things. It is incredible what they have comprehended in this way, for what books can say of histories, laws, ceremonies, and business accounts... is provided very precisely by the quipu," wrote a Spanish colonial observer. This 51-strand quipu is typical of surviving examples, which date from the 13th and 16th centuries.