how do you know which syllables to stress for the meter?

[fajfall]

eg. When reading "I know a bank where the wild thyme blows" I don't know why it's stressed as Boom ba-ba Boom ba-ba Boom Boom Boom (like the William Tell Overture). I wouldn't pick it up unless it were told to me, as I'd assumed iambic pentameter simply repeats Boom-ba or ba-Boom five times per line.

and I don't know why iambic pentameter should be any more favoured than say tetra meter or hexameter. I read it suits the English language more but I still don't get it.

[desiresjab]

First, you listen to yourself read the line several times. Every word is one syllable. You will notice the words "know a" and "where the" are said twice as fast as other single words in the line. Technically, if you know music, those two phrases are made of two sixteenth notes apiece. Every other word in the line is an eighth note, except for the last note, which is a full quarter note before beginning the next line quite naturally, whether one follows William Tell or simply the natural way speakers would read this. Ba ba's are sixteenth notes, and never accented. I suppose you could find a rare case. The pauses, the caesuras, are all quite natural.

Slowly tap your foot as you say the line now. When you get a little mechanical and say it "in time," you see it is a perfect musical measure of four beats.

"I know a" is one poetic foot, an 8th note followed by two 16th notes.

"place where the" is an identical poetic foot

"wild thyme" is two eighth notes, upbeat/downbeat of your foot.

"grows" i a quarter note, meaning it lasts a full beat, included with the short duration of it natural caesura, of course.

* * * * *

Even an urgent triplet feel can be found successfully employed among the masters.

Early in the morning the dark queen said:
"The trumpets are warning there's trouble ahead.

Louis Simpson