My glass shall not persuade me I am old,
So long as youth and thou are of one date;
But when in thee time's furrows I behold,
Then look I death my days should expiate.
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In the sonnet, the speaker of the poem and a young man are represented as enjoying a healthy and positive relationship. The last line, however, hints at the speaker's doubts, which becomes prominent later in the sequence.
The poet can see some traces of advancing age when he looks in a mirror; but he is united so closely to his friend, that he will not believe that he is himself old, while his friend is in the bloom of youthful beauty.