Synthesis of William Shakespeare's Sonnet 18 involves several key aspects: comparison, contrast, and the establishment of poetry as a means of achieving immortality. The poem revolves around the speaker's contemplation of comparing his beloved to a summer's day, ultimately concluding that the subject of the poem surpasses summer in beauty and constancy.Comparison to a Summer's DayThe sonnet begins with the speaker questioning whether he should compare his beloved to a summer's day. He quickly asserts that his beloved is "more lovely and more temperate" than a summer's day. Summer is portrayed as being subject to rough winds, a short duration, and the extremes of heat and cloud cover.Contrast and PermanenceThe poem establishes a contrast between the fleeting nature of summer and the eternal beauty of the person being addressed. The "eternal summer" of the beloved will not fade, nor will it lose its beauty. The speaker suggests that death will not be able to claim the youth because he will live on through the poem's "eternal lines".Immortality Through VerseShakespeare introduces the idea that his poetry provides an alternative form of immortality for the fair youth. As long as people can breathe and see, the poem will live on, giving life to the subject's memory. The poem itself becomes a means of preserving beauty and ensuring that the fair youth is not forgotten.