[105] ‘dicunt, ut scis, Stoici nostri, duo esse in rerum natura, ex quibus omnia fiant, causam et materiam. materia iacet iners, res ad omnia parata, cessatura si nemo moveat; causa autem, id est ratio, materiam format et quocunque vult versat’ Sen. _Ep._ 65, 2; ‘universa ex materia et ex deo constant. deus ista temperat, quae circumfusa rectorem sequuntur. potentius autem est ac pretiosius quod facit, quod est deus, quam materia patiens dei’ _ib._ 23. [106] ἄλλων δὲ καὶ ποιητικὴν μὲν αἰτίαν ἀπολειπόντων, ἀχώριστον δὲ ταύτην τῆς ὕλης, καθάπερ οἱ Στωϊκοί Syrianus _Arist. met._ (Arnim ii 308). ‘Stoici naturam in duas partes dividunt, unam quae efficiat, alteram quae se ad faciendum tractabilem praebeat. in illa prima esse vim sentiendi, in hac materiam; nec alterum sine altero [esse] posse’ Lact. _Div. inst._ vii 3. [107] ‘neque enim materiam ipsam cohaerere potuisse, si nulla vi contineretur, neque vim sine ulla materia’ Cic. _Ac._ i 6, 24. [108] Arnim ii 418; ‘e quibus [elementis] aer et ignis movendi vim habent et efficiendi; reliquae partes accipiendi et quasi patiendi, aquam dico et terram’ Cic. _Ac._ i 7, 26. [109] κατὰ τοὺς Στωϊκούς, ἐκ τῆς τῶν τεσσάρων στοιχείων κράσεως γινομένου τοῦ σώματος Justin _de res._ 6 (Arnim ii 414). [110] ὅσα τοίνυν σώματα πρῶτον τὰς τοιαύτας ἔχει ποιότητας, ἐκεῖνα στοιχεῖα τῶν ἄλλων ἁπάντων ἐστὶ καὶ τῆς σαρκός· ἔστι δὲ ταῦτα γῆ καὶ ὕδωρ καὶ ἀὴρ καὶ πῦρ Galen _const. art. med._ i p. 251 K (Arnim ii 405). [111] Galen _meth. med._ i 2, X p. 15 K (Arnim ii 411). [112] See below, § 196. [113] Cf. Mahaffy’s _Greek Life and Thought_; ‘it is quite wrong to suppose that these thinkers [Zeno and Epicurus], busy as they were with practical life, despised or avoided speculation. Their philosophical theories demand hard reading and hard thinking’ p. 137. CHAPTER VIII. THE UNIVERSE. [Sidenote: Study of the heavens.]