Theme:     Young Man
Content:   A follow-on from Sonnet 13 & 14 providing a far more subtle and disguised encouragement for the subject to father children.

• "When I consider that all living things hold perfection for just a moment in their life and that the world has nothing but showy things on which the heavens secretly observe and pass comment."
• Repeat of the significance of holds from Sonnet 13 signifying the temporary hold that a subject has on their beauty.
• The play on the significance of stars is extended from Sonnet 14 with several words for which st is significant.
• This first quatrain is centred on what the speaker thinks: When I consider.

• "When I see men, like plant life, change with the weather and achieve youthful climax then diminish as they age."
• Possible play on "conceive" in the con of Q1 and perceive in Q2.
  
• Stars again echoed in state.
• This second quatrain is centred on what the speaker sees: When I perceive.
• The sentiments of the first 2 quatrains, with their likening of human life to plants and the brevity of life being held in perfection, echo the Burial of the Dead section of the Book of Common Prayer: "Man that is born of a woman hath but a short time to live, and is full of misery. He cometh up, and is cut down, like a flower; he fleeth as it were a shadow, and never continueth in one stay".

• "You are now rich in youth but will inevitably grow old."
• The first 2 quatrains opened with When and the third shifts to Then.
• The first 2 quatrains' words consider and perceive are now combined to create conceit, almost "conceive".
• Mid-line rhyme of wasteful with sullied.
• Repeat of many key words from Sonnet 14 driving home the same sentiments.
• This quatrain now turns its attention to the subject having set the scene of the broader picture earlier with emphasis on you words. This is rather like a single panoramic film shot panning the sky and then gravitating down to ultimately focus on the single subject.
• Stars again echoed in inconstant, stay, most and wasteful.
• The nought of Q1 now morphs to night, something unwelcome but at least something of substance and better than nothing/nought.

• "As time takes away your youth, I use that time to graft new ones (children) on you via my verse."
• The plant analogy concludes with the use of the word engraft and the verse itself literally grafts the word new onto the subject.
• The night of Q2 now morphs to new, something very welcome, of substance and far better than nought or night.
• The rhyme of new with you emphasises the plea to the subject of creating a new you.