What is the effect that alliteration has on MLKs speech

There passed, as a shroud  

A fleecy cloud,  

And I turned away to thee, - The night is changeable

I gazed awhile.  

On her cold smile;  

Too cold—too cold for me— - Moonlight can be uninviting

And dearer thy beam shall be;  

For joy to my heart  

Is the proud part

Thou bearest in Heaven at night, - Stars evoke wonder

Explanation:

In this poem, "Evening Star" by Edgar Allen Poe, a fleecy cloud passing by the moon at night changes the view of the speaker. His gaze falters and he turns away from the "cold smile" of the moon to look at the evening star. This could represent how the night is changeable in its views, how things are constantly moving and changing- every slight passing of a cloud, variation in the moonlight, appearance of the stars, their positions, etc. It could also represent how the changing night changed the speaker's gaze.

The speaker doesn't connect to moon well and calls her smile "cold", "too cold," and despite it being brighter than the stars, calls her moonlight "pale" and "lowly." He describes the moon as residing among her "slaves"- the planets, and presents the moon in an image of coldness and arrogance. Hence, moonlight, for him, is uninviting.

The speaker's heart is filled with joy when he looks at the evening star. He says that the beam of the star is "dearer" to him even if it is so far away. His affection towards it is all the more because of the distance, despite which its light reaches him, and the significant part the star has in the night sky or the "Heaven," according to him. He admires and prefers its "distant fire." All this adds to the sense of how the stars evoke wonder by the virtue of their light, distance, position and personal significance to the speaker.