Proclus, the scholiast to Euclid, knew Eudemus of Rhodes' History of Geometry well, and gave a short sketch of the early history of geometry, which appeared to be founded on the older, lost book of Eudemus. The passage has been referred to as "the Eudemian summary," and determines some approximate dates, which otherwise might have remained unknown. The influential commentary on the first book of Euclid's Elements of Geometry is one of the most valuable sources we have for the history of ancient mathematics, and its Platonic account of the status of mathematical objects was influential. In this work, Proclus also listed the first mathematicians associated with Plato: a mature set of mathematicians (Leodamas of Thasos, Archytas of Taras, and Theaetetus), a second set of younger mathematicians (Neoclides, Eudoxus of Cnidus), and a third yet younger set (Amyntas, Menaechmus and his brother Dinostratus, Theudius of Magnesia, Hermotimus of Colophon and Philip of Opus). Some of these mathematicians were influential in arranging the Elements that Euclid later published. Lost Works A number of his Platonic commentaries are lost. In addition to the Alcibiades, the Cratylus, the Timaeus, and the Parmenides, he also wrote commentaries on the remainder of the dialogues in the Neoplatonic curriculum. He also wrote a commentary on the Organon, as well as prolegomena to both Plato and Aristotle. Legacy Proclus exerted a great deal of influence on Medieval philosophy, though largely indirectly, through the works of the commentator Pseudo-Dionysius the Areopagite. This late-5th- or early-6th-century Christian Greek author wrote under the pseudonym Dionysius the Areopagite, the figure converted by St. Paul in Athens. Because of this fiction, his writings were taken to have almost apostolic authority. He is an original Christian writer, and in his works can be found a great number of Proclus's metaphysical principles. Another important source for the influence of Proclus on the Middle Ages is Boethius's Consolation of Philosophy, which has a number of Proclus principles and motifs. The central poem of Book III is a summary of Proclus's Commentary on the Timaeus, and Book V contains the important principle of Proclus that things are known not according to their own nature, but according to the character of the knowing subject. A summary of Proclus's Elements of Theology circulated under the name Liber de Causis (the Book of Causes). This book is of uncertain origin, but circulated in the Arabic world as a work