Themes in Sonnet 18

After discussing the different means by which the fair youth’s beauty might be preserved, the speaker ends with a statement of the power of poetry. The poem reflects back on itself, for the speaker claims that “this gives life to thee.” “This” refers to this very sonnet. The separation between the poem and the world within the poem collapses. The speaker is the poet. Shakespeare employs this literary move throughout the sonnet sequence, referring often to the immortality of his own work. As long as his work continues to be read, Shakespeare’s claims ring true.

The use of “grow’st” at the end of the line reveals an additional interpretation of “lines.” The poem itself, with its power to immortalize the youth, attaches him to time as if he were a scion, a grafted plant shoot. Thus “eternal lines” can take on a literal reference to tree branches. This metaphor evokes once again the thematic use of the natural world while deepening the idea of poetry as procreation.

“Eternal lines” takes on multiple interconnected meanings. The “lines” can refer to lines of poetry, referring to the speaker’s desire to preserve the fair youth through verse. The “lines” can also refer to genetic lineage, another means by which the fair youth can preserve his own image through time. Shakespeare seems to be equating these two lines, artistic and genetic. In the preceding poems, the speaker urged the youth to procreate; now the speaker weighs the benefits of poetry as a means of passing on the youth’s essence.

This line evokes both Judeo-Christian and Greco-Roman conceptions of death. The “shade” can be read as a reference to Psalm 23: “Yea, though I walk through the valley of the shadow of death, I will fear no evil: for thou art with me.” This reference frames the youth’s life in spiritual terms: his fairness extends to his soul, and thus he is worthy of salvation. The personification of death is a device from Greco-Roman tradition, as is the use of “shade” as human soul. This separation of soul from body relates to the poem’s central theme. Physical beauty fades and dies, but the fair youth’s essence can be captured and memorialized through poetry.

Throughout the sonnets, the speaker compares a lifespan to the changing seasons of the year. “Summer” represents the period of early adulthood while winter symbolizes old age and the end of one’s life.