Assonance and alliteration

Assonance

"Early Moon" is a poem by Carl Sandburg. In this excerpt, the long "o" sounds old or mysterious partly because it helps slow the rhythm.

"Poetry is old, ancient, goes back far. It is among the oldest of living things. So old it is that no man knows how and why the first poems came."

Assonance can be hard to find because it's subtle. The long vowel sounds will slow down the energy and make the mood more somber, while stressed sounds can increase the energy level. 

Notice how the mood is set by using the long "A" in this excerpt from Cormac McCarthy's book, Outer Dark:

"And stepping softly with her air of blooded ruin about the glade in a frail agony of grace she trailed her rags through dust and ashes, circling the dead fire, the charred billets and chalk bones, the little calcined ribcage."

The words "glAde," "frAil," "grAce," and "trAiled" help set the chilling mood of the work, and it is repeated and emphasized at the end with "ribcAge."

Dylan Thomas' poem "Do Not Go Gentle into the Good Night" touches upon the subject of death and also sets the mood by using assonance as a literary tool:

"Do not go gentle into that good night, Old age should burn and rave at close of day; Rage, rage, against the dying of the light. . . .Grave men, near death, who see with blinding sight. Blind eyes could blaze like meteors and be gay, Rage, rage against the dying of the light."

Alliteration isn't just about tongue twisters. Here are two examples of literary alliteration.

"Whereat, with blade, with bloody blameful blade, He bravely breach'd his boiling bloody breast." from Shakespeare's "A Midsummer Night's Dream"

Dancing Dolphins/Those tidal thorough/breds that tango through the turquoise tide./Their taut tails thrashing they twist in tribute to the titans./They twirl through the trek tumbling towards the tide./Throwing themselves towards those theatrical thespians. - Paul McCann

Edgar Allan Poe was a master of assonance, consonance, and alliteration. Here is one line from the poem The Raven that has all three devices. Can you spot them?

"And the silken sad uncertain rustling of each purple curtain"