Ancient Greek text
Ἐπειδὴ τὸ μὲν αἰσθάνεσθαί τε καὶ κινεῖσθαι κατὰ προαίρεσιν ἴδια τῶν ζώων …
Claudii Galeni Opera Omnia, Knobloch, Leipzig, 1821
Galen, De naturalibus facultatibus, ed. Karl Gottlob Kühn. 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.
Other editions: A. J. Brock
Texts from The Greek Library and the Perseus Digital Library, under CC BY-SA 4.0 and CC BY 4.0. Divided into reading sections by Interlinea.