Shakespeare uses a series of metaphors to explore one of the central riddles of existence: how one escapes the vagaries of time and death. The tone of the sonnet is melancholy, as if the speaker is resigned to mortality and the forward march of time. The poem opens with the intriguing phrase “like as” (Line 1), suggesting what is to follow is a simile. Readers might wonder about the double comparative “like” and “as” when either word alone would be sufficient. Shakespeare cleverly uses both to maintain the iambic (five stresses) pentameter of his line, ensuring it has the extra stress of “like.” But that is not the only reason for the particular phrasing. By using both “like” and “as,” the poet introduces the theme of life-as-repetition, which is central in the poem. The nearly interchangeable words foreshadow the interchangeable nature of waves and minutes, the dominant image of the first four lines of the sonnet.

The poet chooses the image of waves crashing against the shore to describe the progress of moments; what makes this image especially powerful is its repetitive motion. Waves swell and die, one after the other.