Stress, Unstress, Repeat

“As a stressed syllable ends, other things being equal, to be pronounced with higher pitch than weak syllables, a purely ‘iambic’ line will tend towards a higher tone at the end, but according to general phonetic laws this is a sign that something more is to be expected. Consequently it is in iambic verses easy to knit line to line in natural continuation.” – Otto Jesperson, Notes On Metre, 1933