Cl. Gal.De vsu partium corporis humani, libri 17. Nicolao Regio Calabro interprete,
ex plurium Graecorum exemplarium collatione castigatiores quàm vnquam alias.
Lvgdvni 1550

Περὶ χρείας τῶν ἐν ἀνθρώπου σώματι μορίων
editio critica: Helmreich, 1907

De l'usage des parties du corps humain, livres XVII Efcrits par CLAVDE GALIEN,
& traduits fidelement du Grec en François
par J. Dalechamps. Paris 1609

Oeuvres anatomiques, physiologiques et médicales de Galien
par le Dr. Ch. Daremberg, Paris 1854
think rather of that straight line as you would of a thin hair or the filament of a cobweb accurately stretched from the pupil to the center of the circle. Again, from the pupil to the line which bounds the circle and is also called its circumference imagine a series of very many other lines extending like thin cobwebs. Call the figure bounded by al these straight lines and by the circle a cone, and think of the pupil as its apex and the circle as its base.