“The heart is sinewy, muscular and full of veins, having arteries as well. It is conical in shape, somewhat fatty; the arteries and veins, through which blood and pneuma are distributed, grow out from it. In another way: the heart is muscular, having a conical shape and two ventricles, in which are generated the innate heat and the vital pneuma. The arteries grow out from it, also the veins grow out from it. Through these, both the life-bearing seed and the innate heat are supplied to the whole body.”

Καρδία ἐστὶ νευρώδης καὶ μυώδης καὶ φλεβώδης, ἔχουσα καὶ ἀρτηρίας. κωνοειδὴς τῷ σχήματι, ὑποπίμελος, ἐξ ἧς ἐκπεφύκασιν ἀρτηρίαι καὶ φλέβες δι' ὧν ἐπιπέμπεται αἷμα καὶ πνεῦμα. ἄλλως. καρδία ἐστὶ μυώδης, ἔχουσα σχῆμα κωνοειδὲς καὶ δύο κοιλίας ἐν αἷς γεννᾶται τὸ ἔμφυτον θερμὸν καὶ τὸ ζωτικὸν πνεῦμα. ἐξ ἧς ἐκπεφύκασιν ἀρτηρίαι καὶ φλέβες ἐκφύονται. δι' ὧν χορηγεῖται τῷ παντὶ σώματι ὅ τε ζωτικὸς γόνος καὶ ἡ ἔμφυτος θερμασία.

Ps.-Galen, Medical Definitions 49 (XIX 360 Kühn)