Shakespeare's sonnet has the same theme as Sonnet 75 by Spenser: the poet makes his beloved immortal by means of his poetry. This theme is a conventional one in Elizabethan sonnets. But Shakespeare and Spenser treat it in an original and individual manner. Spenser starts from a concrete situation and uses dialogue to make his point. Shakespeare writes a monologue in the form of an address. It contains a carefully reasoned argument which, as in many of Shakespeare's sonnets, moves in a series of steps.
The first line, a question, proposes a comparison between Shakespeare's beloved and a summer season. Summer is chosen because it is lovely and pleasant. In the second line the comparison is restricted: in outward appearance and character the beloved person is more beautiful and less extreme than summer. The reasons for the restriction are given in the next four lines which describe the less pleasant aspects of summer. In the seventh and eighth lines Shakespeare complains that every beauty will become less one day. The ninth line takes up the comparison with summer again: summer has by now become the summer of life.
The comparison turns into a contrast by referring back to the seventh. The poet's assurance becomes even firmer in lines eleven and twelve, which contain a promise that death will be conquered. 'Eternal lines' refers to lines of poetry but also suggest lines of shape. It points forward to the triumphant couplet which explains and summarizes the theme: poetry is immortal and makes beauty immortal.
Because of the step by step arguments Shakespeare's conclusion makes the impression of great certainty. His method is more rational and logical than Spenser's. Spenser does not try to argue or prove his theme. Shakespeare wrote a series of sonnets, most of which were probably addressed to a noble young man for whom he felt deep love and admiration. In many of them he deals with the problem of time, sometimes optimistically as in the present sonnet, sometimes in a mood of despair. Essay on Shakespeare's Sonnet 18 By: david William Shakespeare!.