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).
(c) Both consonants may occur at the beginning of the second word. If the vowel is naturally short, the syllable is almost always short, though such scansions as σε̄ κτενω are occasionally found. But if the second word begins with a double consonant or σ followed by another consonant, the syllable is always long. Thus ο̄ ξενος, τῑ ζητεις, ταυτᾱ σκοπουμεν.
A vowel, naturally short, when thus lengthened is said to be “lengthened by position.”