The villain Edmund sets the father against the son. Gloucester, lost in a reverie, repines, and on his exit is rebuked by his bastard son:

GLOUCESTER These late eclipses in the sun and moon portend 
no good to us: though the wisdom of nature can 
reason it thus and thus, yet nature finds itself 
scourged by the sequent effects: love cools, 
friendship falls off, brothers divide: in cities, mutinies; 
in countries, discord; in palaces, treason; and the bond cracked 
'twixt son and father. This villain of mine comes under the prediction; 
there's son against father: the king falls from bias of nature; 
there's father against child. We have seen the best of our time: 
machinations, hollowness, treachery, and all ruinous disorders,
follow us disquietly to our graves. Find out this villain, Edmund;
 it shall lose thee nothing; do it carefully. 
And the noble and true-hearted Kent banished! his offence, honesty! 
'Tis strange. 

Exit 

EDMUND This is the excellent foppery of the world,
 that, when we are sick in fortune,--often the surfeit 
of our own behavior,--we make guilty of our disasters the sun, 
the moon, and the stars: as if we were villains by necessity; 
fools by heavenly compulsion; knaves, thieves, and treachers, 
by spherical predominance; drunkards, liars, and adulterers, 
by an enforced obedience of planetary influence; and all 
that we are evil in, by a divine thrusting on: 
an admirable evasion of whoremaster man, to lay his goatish 
disposition to the charge of a star! My father compounded
with my mother under the dragon's tail; and my nativity 
was under Ursa major; so that it follows, I am rough and lecherous. 
Tut, I should have been that I am, had the maidenliest star 
in the firmament twinkled on my bastardizing

So much beauty, and I really can't tell you why. 

The other day I a did reading from The Beautiful Struggle, and a young lady, noting the rhythm of the text, used the word "assonance." I listened to her and thought to myself, "I have no idea what that means." And I felt like an idiot. Here was a woman complimenting me, and I was too ignorant to really get the import. 

It's the funniest thing. I write by ear and have only slightest notion why a particular assembly of words sounds good, while still another does not. Sometimes I dearly wish I knew and other times I just enjoy turning it under my tongue like a peppermint. 

Answers are not always the point. And even the answers dispensed in labels--off-rhyme, dissonance, iambic pentameter etc.--don't do the question justice. They can tell you what it is, but not why this...

...though the wisdom of nature can 
reason it thus and thus, yet nature finds itself 
scourged by the sequent effects: love cools, 
friendship falls off, brothers divide: in cities, mutinies; 
in countries, discord; in palaces, treason; and the bond cracked 
'twixt son and father...

...just feels good. The rhythm, itself--beyond plot, beyond character--says something.