abstract:The Centiloquium (= "one hundred sayings"), also called Ptolemy's Centiloquium, is a collection of one hundred aphorisms about astrology and astrological rules. It is first recorded at the start of the tenth century CE, when a commentary was written on it by the Egyptian mathematician Ahmad ibn Yusuf al-Misri (later sometimes confounded with his namesake Ali ibn Ridwan ibn Ali ibn Ja'far al-Misri, or in Latin "Haly ibn Rodoan", who lived a century later and wrote a commentary on Ptolemy's Tetrabiblios).