# Opticorum recensio Theonis ια΄.

Euclid, Opticorum recensio Theonis, ια΄.. Ancient Greek.

Canonical: https://interlinea.aeterna-institute.org/library/greek/euclid/opticorum-recensio-theonis/%CE%B9%CE%B1%CE%84.

Τῶν ἄνω τοῦ ὄμματος ἐπιπέδων κειμένων τὰ πόρρω ταπεινότερα φανεῖται. ἔστω γὰρ ὄμμα τὸ Β κάτω τοῦ ∠Ζ ἐπιπέδου κείμενον, ἀφʼ οὗ προσπιπτέτωσαν ἀκτῖνες αἱ Β∠, ΒΓ, ΒΖ, ὧν ἡ ΒΖ κάθετος ἔστω ἐπὶ τὸ ὑποκείμενον ἐπίπεδον. λέγω, ὅτι τὸ Γ`∠ τοῦ ΓΖ ταπεινότερον φαίνεται. διὰ δὴ τὸ προεκτεθὲν θεώρημα ταπεινοτάτη τῶν ἀπὸ τοῦ Β ὄμματος πρὸς τὸ ∠ ἐπίπεδον προσπιπτουσῶν ἀκτίνων ἐστὶν ἡ Β∠, ἡ δὲ Β τῆς ΒΖ ταπεινοτέρα. ἀλλὰ διὰ μὲν τῶν Β∠, ΒΓ ἀκτίνων τὸ ∠Γ φαίνεται, διὰ δὲ τῶν ΒΓ, ΒΖ τὸ ΓΖ. τὸ ∠Γ ἄρα ταπεινότερον τοῦ Γ Ζ ὁρᾶται.

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Euclid, Opticorum recensio Theonis, ed. Johan Ludvig Heiberg, Heinrich Menge. Text: The Greek Library, from the Perseus Digital Library and other open sources, CC BY-SA 4.0. Changes: apostrophes normalised and the text divided into reading sections by Interlinea.
License: CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0/). Source: https://thegreeklibrary.pages.lisn.upsaclay.fr/works/tlg1799.tlg010.local001/.