Greek metre is based, not upon stress-accent,[858] but upon quantity—the length of time needed for the pronunciation of a syllable. In English the line My bosom’s lord sits lightly in his throne is “scanned” (that is to say, marked off into “feet”—the metrical units) as a series of five iambi; the iambus being a foot which consists of an unaccented, followed by an accented, syllable. The word “bosoms” can stand where it does because the stress of the voice naturally falls upon the first syllable of “bosom”; to begin a line with “my seréne bosom” would clearly be wrong. The _length_ of the syllables has no effect on the scansion. That “sits” needs as long a time for its utterance as the first syllable of “lightly” does not alter the fact that “sits light-” is an accentual iambus. Greek words, on the other hand, as metrical material, are considered only from the quantitative point of view, not the accentual. The voice-stress in the word λόγους rests upon the first syllable, but the word is an iambus, a “short” followed by a “long” (marked respectively thus ⏑–). Whereas an English blank verse consists of five accentual iambi, _e.g._ To ént|ertaín | divíne | Zenócr|até, the corresponding verse of all the Greek dramatists is composed of six feet each of which is theoretically a quantitative iambus, and most of which actually are such. Thus _Andromache_, v. 241 is to be scanned ⏑ – ⏑ – ⏑ – ⏑ – ⏑ – ⏑ – τι δ ου | γυναιξ|ι ταυτ|α πρωτ|α παντ|αχου. When is a syllable long and when short? A few rules will settle all but a minority. _All_ syllables are long— (i) Which contain a necessarily long vowel (η or ω), _e.g._ μη̄ν, τω̄ν. (ii) Which contain a diphthong or _iota_ subscript, _e.g._ ο̅ι̅νος, α̅ι̅νο̅υ̅μεν, ρᾳ̅διως; save that the first syllable of ποιῶ and τοιοῦτος (and their parts) is often short. (iii) Which end with a double consonant (ζ, ξ, ψ), _e.g._ ο̄ζος, ε̄ξω, ε̄ψαυσα. (iv) Which have the circumflex accent, _e.g._ υμῖ̅ν, μῦ̅ς. _Most_ syllables are long the vowel of which is followed by two consonants. But there is some difficulty about this very frequent case. It can arise in three ways:— (_a_) Both consonants may be in the same word as the vowel. Then the syllable is long, save when the consonants are (i) a voiced stop (β, γ, δ) followed by ρ; or (ii) a voiceless stop or spirant (κ, π, τ; θ, φ, χ) followed by a liquid or nasal (λ, ρ, μ, ν)—in both of which cases the syllable can be counted long or short at pleasure. Thus ε̄σμεν, μο̄ρφη, ᾱνδρος; but the first syllables of ιδρις, τεκνον, ποτμος are “doubtful”—they can be either long or short as suits the poet. (_b_) One of the consonants may end its word and the other begin the next. Such syllables are _all_ long. Thus, τηκτο̄ς μολυβδος, ανδρε̄ς σοφοι, although both these long syllables are “short by nature” (see below).