Using LIDDS which three should I use in a compare/contrast essay of the poems "To the Mercy Killers" and "Do Not Go Gentle into That Good...

In these two poems, imagery seems to be most
important.

The images in both poems are very powerful.
Randall uses some rather difficult images to describe the speaker's decaying
body:

Even
though I be a clot, an aching clench,
a stub, a stump, a butt, a scab, a
knob,
a screaming pain, a putrefying stench,
still let me live, so
long as life shall
throb.

Here, the speaker
dictates the truth of death. His imagery (and diction and language) illustrate that he
knows how bad it will be, if someone is questioning whether or not to kill him out of
mercy. He knows what it will be like and is able to support his cause that he wants to
continue under the direction of his own mind and body.

The
speaker in Thomas's poem also uses imagery to fight against
death:

Wild
men who caught and sang the sun in flight,
And learn, too late, they grieved
it on its way,
Do not go gentle into that good
night.

The important image
here is the sun in flight. We can envision the wild men and what they are like,
"sing[ing] the sun in flight."