"Identical intervals make a regular rhythm. The more irregular intervals there are, the more alike the events have to be for any rhythm to be recognised." Le Guin observes that poems seldom have more than two unstressed syllables between stresses, whereas prose often has three or more unstressed syllables as intervals. This is quite a useful distinction between poetry and prose. Le Guin questions the usefulness of the metrical foot. She'd rather break the line into bars, which represent syntactical groupings. I actually like this better and it makes more sense to me. I also like how she marks the stresses by simply capitalizing the letters. It is easier to read than the conventional stress marks. Ursula K. Le Guin, "Stress-Rhythm in Poetry and Prose"