«Against my love shall be, as I am now,
With Time’s injurious hand crush’d and o’er-worn».
References to the young man’s future are signs of the poet’s fear that love cannot defend against time.
Against my love shall be, as I am now,
The youth could die — “When hours have drained his blood” — and so could his beauty — “And all those beauties whereof now he’s king / Are vanishing, or vanished out of sight” — but when the youth is as agedas the poet, the youth’s former good looks will be preserved in the poet’s verse.
“Confounding age’s cruel knife,” which recalls Sonnet 60’s “And Time that gave doth now his gift confound,” is no match against the poet’s sonnets, “these black lines” in which the young man will forever live “still green.”
English audio from YouTube Channel Socratica
Summary from Cliffsnotes.com