because the latter are conjectural while only the former can secure certain knowledge. This view is contrary to the Platonic and Aristotelian traditions, where theology or metaphysics occupied the highest honour. Despite being a minority position among ancient philosophers, Ptolemy's views were shared by other mathematicians such as Hero of Alexandria. Named after Ptolemy There are several characters or items named after Ptolemy, including: The crater Ptolemaeus on the Moon The crater Ptolemaeus on Mars The asteroid 4001 Ptolemaeus Messier 7, sometimes known as the Ptolemy Cluster, an open cluster of stars in the constellation of Scorpius The Ptolemy stone used in the mathematics courses at both St. John's College campuses in the U.S. Ptolemy's theorem on distances in a cyclic quadrilateral, and its generalization, Ptolemy's inequality, to non-cyclic quadrilaterals Ptolemaic graphs, the graphs whose distances obey Ptolemy's inequality Ptolemy Project, a project at University of California, Berkeley, aimed at modeling, simulating and designing concurrent, real-time, embedded systems Ptolemy Slocum, actor Works Planisphaerium, medieval Arabic translations and an English translation thereof, https://www.sciamvs.org/files/SCIAMVS_08_037-139_Sidoli_Berggren.pdf See also Equant Messier 7 – Ptolemy Cluster, star cluster described by Ptolemaeus Pei Xiu Ptolemy's Canon – a dated list of kings used by ancient astronomers. Ptolemy's table of chords Zhang Heng Footnotes References Berggren, J. Lennart, and Alexander Jones. 2000. Ptolemy's Geography: An Annotated Translation of the Theoretical Chapters. Princeton and Oxford: Princeton University Press. . Hübner, Wolfgang, ed. 1998. Claudius Ptolemaeus, Opera quae exstant omnia Vol III/Fasc 1: ΑΠΟΤΕΛΕΣΜΑΤΙΚΑ (= Tetrabiblos). De Gruyter. (Bibliotheca scriptorum Graecorum et Romanorum Teubneriana). (The most recent edition of the Greek text of Ptolemy's astrological work, based on earlier editions by F. Boll and E. Boer.) Lejeune, A. (1989) L'Optique de Claude Ptolémée dans la version latine d'après l'arabe de l'émir Eugène de Sicile. [Latin text with French translation]. Collection de travaux de l'Académie International d'Histoire des Sciences, No. 31. Leiden: E.J.Brill. Nobbe, C. F. A., ed. 1843. Claudii Ptolemaei Geographia. 3 vols. Leipzig: Carolus Tauchnitus. (Until Stückelberger (2006), this was the most recent edition of the complete Greek text.) Peerlings, R.H.J., Laurentius F., van den Bovenkamp J.,(2017) The watermarks in the Rome editions of Ptolemy's Cosmography and more, In Quaerendo 47: 307–327, 2017. Peerlings, R.H.J., Laurentius F., van den Bovenkamp J.,(2018) New findings and discoveries in the 1507/8 Rome edition of Ptolemy’s Cosmography, In Quaerendo 48: 139–162, 2018. Ptolemy. 1930. Die Harmonielehre des Klaudios Ptolemaios, edited by Ingemar Düring.