«Not from the stars do I my judgment pluck;
And yet methinks I have astronomy,».
Sonnet 13 depends on an intimate relationship between the poet and the young man that is symbolized in the use of the more affectionate “you”; Sonnet 14 discards — at least temporarily — this intimate “you” and focuses on the poet’s own stake in the relationship between the two men.
Not from the stars do I my judgment pluck;
In fact, this sonnet is more about the poet — the “I” — than about the young man. Ironically, the poet appears to be as infatuated with the young man as he claims the young man is infatuated with his own reflection in a mirror.
Sonnet 14 contains one dominant image, that of the young man’s eyes as stars, from which the poet attains his knowledge. Stylistically, this sonnet is a good example of a typical Shakespearean sonnet: The first eight lines establish an argument, and then line 9 turns this argument upside down with its first word, “But.” The concluding couplet, lines 13 and 14, declares some outcome or effect of the young man’s behavior. Typically, this concluding image is of death, as in Sonnet 14’s “Thy end is truth’s and beauty’s doom and date.” In other words, should the young man die without fathering a son, not only will he suffer from the lack of an heir, but the world, too, will suffer from the youth’s selfishness.
English audio from YouTube Channel Socratica
Summary from Cliffsnotes.com