Proclus, "A Commentary on the First Book of Euclid's Elements"
Glenn R. Morrow (trans.), Proclus: A Commentary on the First Book of Euclid’s Elements, Princeton University Press, 1970
All those who have written histories bring to this point their account of the development of this science. Not long after these men came Euclid, who brought together the Elements, systematizing many of the theorems of Eudoxus, perfecting many of those of Theaetetus, and putting in irrefutable demonstrable form propositions that had been rather loosely established by his predecessors. He lived in the time of Ptolemy the First, for Archimedes, who lived after the time of the first Ptolemy, mentions Euclid. It is also reported that Ptolemy once asked Euclid if there was not a shorter road to geometry than through the Elements, and Euclid replied that there was no royal road to geometry. He was therefore later than Plato’s group but earlier than Eratosthenes and Archimedes, for these two men were contemporaries, as Eratosthenes somewhere says. Euclid belonged to the persuasion of Plato and was at home in this philosophy; and this is why he thought the goal of the Elements as a whole to be the construction of the so-called Platonic figures.
Translation from Elementary Ancient Greek I. GRK 101. A. Scholtz, Binghamton University:
For Archimedes as a side note recalls a conversation Euclid once had with Ptolemy [Egyptian king], who asked him if there’s a shortcut to learning geometry, a way to avoid immersing oneslf in the basics. Euclid answered, “There is no royal road to geometry.”
Friedlein, G. (ed.), Procli Diadochi in primum Euclidis elementorum librum commentarii, Bibliotheca scriptorum Graecorum et Romanorum Teubneriana, Teubner, 18731 2
p. 68, ll. 4-23:
οἱ μὲν οὖν τὰς ἱστορίας ἀναγράψαντες μέχρι τούτου προάγουσι τὴν τῆς ἐπιστήμης ταύτης τελείωσιν. οὐ πόλυ δὲ τούτων νεώτερός ἐστιν Εὐκλείδης ὁ τὰ στοιχεῖα συναγαγὼν καὶ πολλὰ μὲν τῶν Εὐδόξου συντάξας, πολλὰ δὲ τῶν Θεαιτήτου τελεωσάμενος, ἔτι δὲ τὰ μαλακώτερον δεικνύμενα τοῖς ἔμπροσθεν εἰς ἀνελέγκτους ἀποδείξεις ἀναγαγών. γέγονε δὲ οὗτος ὁ ἀνὴρ ἐπὶ τοῦ πρώτου Πτολεμαίου· καὶ γὰρ ὁ Ἀρχιμήδης ἐπιβαλὼν καὶ τῷ πρώτῳ μνημονεύει τοῦ Εὐκλείδου, καὶ μέντοι καί φασιν ὅτι Πτολεμαῖος ἤρετό ποτε αὐτόν, εἴ τίς ἐστιν περὶ γεωμετρίαν ὀδὸς συντομωτέρα τῆς στοιχειώσεως· ὀ δὲ ἀπεκρίνατο, μὴ εἶναι βασιλικὴν ἀτραπὸν ἐπὶ γεωμετρίαν· νεώτερος μὲν οὖν ἐστι τῶν περὶ Πλάτονα, πρεσβύτερος δὲ Ἐρατοσθένους καὶ Ἀρχιμήδους. οὗτοι γὰρ σύγχρονοι ἀλλήλοις, ὥς πού φησιν Ἐραροσθένης. καὶ τῇ προαιρέσει δὲ Πλατωνικός ἐστι καὶ τῇ φιλοσοφίᾳ ταύτῃ οἰκεῖος, ὅθεν δὴ καὶ τῆς συμπάσης στοιχειώσεως τέλος προεστήσατο τὴν τῶν καλουμένων Πλατωνικῶν σχημάτων σύστασιν.