In almost all English poetry since the time of Chaucer (fl. 1370-1400), as in medieval and modern European poetry generally, metre, i.e., poetic rhythm, is constituted by the pattern of stressed and unstressed syllables in a line of verse. By contrast, in the poetry of Classical Greece and Rome and in Classical Arabic poetry, to name three traditions of which AWE is aware, metre is constituted not by the pattern of stressed and unstressed syllables but by the pattern of long and short syllables in a line of verse. To put the point in slightly more technical language, Classical Greek, Latin, and Arabic poetry employs quantitative metre, i.e., metre based on the quantity (or 'length') of the syllables in the words which make up a line of verse. (The convenient term for the usual English patterns of stressed and unstressed syllables is qualitative metre.)
In fact the English terms for the different types of metrical foot - dactyl, spondee, trochee, and so on - were first used in connection with Greek and Latin poetry and designated metrical feet whose pattern is based on the quantity of the syllables they contain. So, for example, in the context of quantitative metre, a dactylic foot consists of three syllables of which the first is long, and the second and third are short.
The rule which determines the 'length' or quantity of a syllable in Greek and Latin poetry is that a syllable is long if it contains either a long vowel or a diphthong or a vowel followed by two or more consonants; otherwise the syllable is short. (The rule is in fact slightly more complicated than this; but in the present context the qualifications do not matter.) To illustrate, here are the opening lines of the Aeneid, the great epic poem by the Roman poet Virgil - Publius Vergilius Maro (70-19 B.C.E.). (Long vowels have a macron (i.e., a line over them), e.g., ā,ō,ū; and short vowels have a breve over them e.g., ă, ĕ, ŏ; long syllables are printed in bold type, and the metrical feet are marked by a vertical line.)
- Armă vĭr|umquĕ că|nō, Trō|iae quī |prīmŭs ăb |ōrīs
- Ītălĭ|am fā|tō prŏfŭ|gus Lāv|īniăquĕ |vēnĭt
[Translation: I sing of arms and the man who, exiled by fate, was the first to come from the shores of Troy to Italy and the Lavinian coast.]
As you will see, many of the feet in these lines are dactyls, and this metre is known as a dactylic hexameter. It consists of six feet of which the first five are dactyls and the sixth is either a trochee or a spondee. However, in the first four feet, but never in the fifth, the poet may, if he wishes, substitute a spondee for a dactyl. The dactylic hexameter is a very common metre in the poetry of Ancient Greece and Rome, especially for long poems. As well as being the metre for Virgil's Aeneid, it is the metre of Homer's two great epic poems, the Iliad and the Odyssey, of many epic poems in Latin (such as the Annales of Ennius (239-169 B.C.E.) and the Thebais of Statius (c40-c96 C.E.)), of the Epistles and Satires of Horace (65-8 B.C.E.), and of the Satires of Juvenal (c60-c140 C.E.)
Another common metre in the poetry of the Ancient World is the (so called) iambic trimeter - a rather misleading name for this metre, since an iambic trimeter in fact contains six iambic feet! (The term iambic trimeter is used because this type of line is felt to contain three 'measures', each 'measure' consisting of two iambic feet.) An iambic trimeter need not consist exclusively of iambic feet (any more than a dactylic hexameter need consist exclusively of dactylic feet): the poet may, if he wishes, substitute a spondee for an iambic in the first, third, and fifth foot of the line. Here is an example of a Latin iambic trimeter:
- Sŭīs |ĕt ip|să Rō|mă vīr|ĭbus |rŭit
[Translation: It is by her own strength that even Rome herself comes to ruin.]
Iambic trimeter is the metre used in the dialogue of Greek tragedies and comedies.
Some English poets have written English verse in quantitative metres. For more see Quantitative metre in English.