The Shakespearean sonnet has a precise rhyme scheme, line length, and other technical elements that define it. This format might seem confining, but within it poets like Shakespeare can develop ideas and images that convey meaning to the reader in a compact form. Shakespeare's Sonnet 60 is a poem about mortality and develops an idea based on images of the passage of time.
The fact that Shakespeare is creating a metaphor for the progress of life is apparent in the opening line in which such a metaphor is made explicit in the image of the waves lapping on the shore:
Like as the waves make towards the pibbled shore,
So do our minutes hasten to their end (1-2).
The poet makes a direct comparison between human life and the waves on the shore. The ocean is often used as a metaphor for life, as in "the sea of life," and here one aspect of the movement of the ocean is selected for what it says about the progress of human life. The ocean has a sense of unchangeability in such a poem, and the lapping waves will be continuing their action long after the human being contemplating them is gone.
The image is complex. The wave makes its way to the shore in the same way "our minutes hasten to their end." The pebbles on the shore are pushed along by the waves, and the pebbles become concrete examples of our minutes,
Each changing place with that which goes before,
In sequent toil all forwards to contend (3-4).
Time only runs in one direction, and each minute is supplanted by the next minute and then lost forever. Like the waves on the shore, the passage of time is inexorable, and nothing can stop it or change the sequence.
The rhyme scheme of the sonnet as a whole is ABAB CDCD EFEF GG, and so the scheme in the first stanza is ABAB. The words "towards" in line 1 and "forwards" in line four link the ideas by sound and part of speech--the waves tend toward the shore and time goes forward in sequence. The long "a" s...