The best and most memorable summary of the difference between an ‘iambic’, a ‘spondee’ and a ‘trochee’, by the author of a marvelous biography of George Herbert. Incidentally, an engaging lesson in poetics.
‘Verse moves along on metaphorical ‘feet’: units with differences of emphasis or stress. ‘Iambics march from short to long,’ wrote Coleridge. In other words they go ‘ti-tum’, short-long. Trochees do the opposite: ‘tum-ti’ or long-short. The spondee is a solemn ‘tum-tum’.’
There, sorted, you’ll never muddle them again.
Source: John Drury, Music at Midnight: The Life and Poetry of George Herbert (London: Penguin Books, 2014), p. xviii