Considering the title you can expect the poem might be about the conception of love.

The poem is organized into an octave and a sestet so it follows the sonnet structure.

In the first line the poet starts telling his lover he must love her for real love and not for particular reasons like the smile, the look or similar things. She explains that this form of love don’t last because is connected to these ephemeral things. The real love instead is not conditioned and real. She must also not to love her only for pity, because this is not real love.

The poet concludes inviting the man to love her only for love’s sake remembering the love never dies.

In the first line you can notice the repetition of long vowel sounds (thou-nought) that gives the idea of the vastity (of the nothing).

In the third line the direct speak starts and you may see the repetition of the adjective (not pronoun) “her” that maybe repeat the concept and underlines the love towards lady’s exterior qualities instead of the love toward the lady herself.

In the second-third quatrain are expressed some contradictions ( beloved - be changed, wrought – unwrought) to mark the instability of the first type of love that is connected to mortal things and so don’t last.

In the last line is retaken the use of long vowel sounds (used in the first line) that makes the sensation of an open space and the vastity of the eternity.

 In this sonnet the poet expresses the brevity of the passion and the love of mortal thing.

She thinks that only the pure and unconditioned love can live forever and transcend the death.