There are essentially two kinds of stress in English: natural stress and emphatic stress. As a rule the root syllables of most verbs and the stem syllables of nouns are strongly stressed. Pronouns, the verb to be, adjectives and numbers are sometimes strongly stressed and sometimes stressed lightly or not at all, according to the general sense of the utterance. In the following sentence, for instance, there are normally three strongly stressed syllables (indicated by italics):
If, however, you are expecting to find some red Worcester Pearmain apples and can only see Bramleys, you might protest (now with four strongly stressed syllables):
Here are some more examples. Normal stress is indicated by italics; words given emphatic stress are underlined as well. If the person you are addressing is convinced that there are no apples left in the house, you might say:
Similarly, out of context, the words “She looked at me as she did love” are open to various possible interpretations and patterns of emphasis. How Keats indicates the appropriate stress-pattern in his poem La Belle Dame Sans Merci will be explained in a later chapter.
The nature of English metre depends on two important facts about stress. In normal English conversation the strongly stressed syllables tend to come at regular intervals of time (time in the musical sense, as perceived by the ear, not intervals of a precise number of milliseconds.) The reason for this regularity is obvious, if you think about it. Unless we are drugged, drunk, or suffering some physiological malfunction of the brain, our bodies most readily and economically work in a rhythmical fashion. Many involuntary actions such as heartbeats and normal breathing, and also most repetitive voluntary actions such as walking and typing, tend to be rhythmical. Even if physically handicapped in some way, while we may alter the rhythm of our typing or our footsteps from dum-dum-dum to di-dum di-dum di-dum, we do not lose rhythm altogether. Only the drunk or drugged or ill stagger in a random fashion; people with arthritis or sprained ankles move with their own idiosyncratic rhythmical pattern. Our bodies, if you like, choose to work rhythmically wherever possible, and this is certainly true in speech.
In different languages the rhythm is imposed in different ways. In French, for example, the syllables tend to come at regular intervals of time — this is particularly noticeable when a French person first learns to speak English — and so the more heavily stressed syllables in French come at erratic intervals. French is a syllable-timed language. In English the converse is true: it is the more strongly stressed syllables that come at regular intervals, and the other syllables tumble higgledy piggledy around them. English is a stress-timed language.
This regularity in the utterance of strongly stressed syllables in English means that in the last example about apples, with four strongly stressed syllables — “There are six green apples on the table” — it takes roughly the same time to say the first phrase of six syllables (“There are six green apples”) as it does to say the second phrase of four syllables (“on the table”). This is because English speech swings steadily from one stressed syllable to the next, and any lightly stressed or unstressed syllables in between are lengthened or shortened to fill the time available. This last example could almost be set out in musical bars as: