§26. _Non modo rerum sed verborum_: cf. 9. _Igitur_ picks up the broken thread of the exposition; so 35, and frequently. _Principes ... ex his ortae_: the Greek terms are ‛απλα and συνθετα, see Arist. _De Coelo_, I. 2 (R. and P. 294). The distinction puzzled Plutarch (quoted in R. and P. 382). It was both Aristotelian and Stoic. The Stoics (Zeller, 187 sq.) followed partly Heraclitus, and cast aside many refinements of Aristotle which will be found in R. and P. 297. _Quasi multiformes_: evidently a trans. of πολυειδεις, which is opposed to ‛απλους in Plat. _Phaedr._ 238 A, and often. Plato uses also μονοειδης for _unius modi_; cf. Cic. _Tim._ ch. VII., a transl. of Plat. _Tim._ 35 A. _Prima sunt_: _primae_ (sc. _qualitates_) is the needless em. of Walker, followed by Halm. _Formae_ = _genera_, ειδη. The word is applied to the four elements themselves, _N.D._ I. 19; cf. also _quintum genus_ below, and _Topica_, 11--13. A good view of the history of the doctrine of the four elements may be gained from the section of Stob. _Phys._, entitled περι αρχων και στοιχειων και του παντος. It will be there seen that Cic. is wrong in making _initia_ and _elementa_ here and in 39 (αρχαι and στοιχεια) convertible terms. The Greeks would call the four elements στοιχεια but _not_ αρχαι, which term would be reserved for the primary Matter and Force. _Aër et ignis_: this is Stoic but _not_ Aristotelian. Aristot., starting with the four necessary properties of matter, viz. heat, cold, dryness, moisture, marks the two former as active, the two latter as passive. He then assigns _two_ of these properties, _one_ active and _one_ passive, to each of the four elements; each therefore is to him _both_ active and passive. The Stoics assign only _one_ property to each element; heat to fire, cold to air (cf. _N.D._ II. 26), moisture to water, dryness to earth. The doctrine of the text follows at once. Cf. Zeller, pp. 155, 187 sq., with footnotes, R. and P. 297 sq. _Accipiendi ... patiendi_: δεχεσθαι often comes in Plat. _Tim._ _Quintum genus_: the note on this, referred to in Introd. p. 16, is postponed to 39. _Dissimile ... quoddam_: so MSS.; one would expect _quiddam_, which Orelli gives. _Rebatur_: an old poetical word revived by Cic. _De Or._ III. 153; cf. Quintil. _Inst. Or._ VIII. 3, 26.