How do I love thee? Let me count the ways.
I & thee: personal address
I love thee to the depth and breadth and height
My soul can reach, when feeling out of sight
Depth and breadth and height: she is hyperbolic n her description of love - it is infinite and immeasureable. Also, the internal rhyme makes it similar to the Lord's Prayer.
For the ends of being and ideal Grace.
I love thee to the level of every day's
Being and ideal Grace: his love makes her feel transcendant.
Most quiet need, by sun and candlelight.
I love thee freely as men strive for right;
By sun and candlelight: not only does she love him at day and at night, but he is her sun - the light of her world.
Freely: it is her choice, she hasn't been forced into this relationship.
I love thee purely, as they turn from Praise.
I love thee with the passion put to use
I love thee is repeated which is anaphora - the repetition of a phrase across several verses. This emphasises the fact that she loves him A LOT.
In my old griefs and my childood's faith.
I love thee with a love I seemed to lose
Old griefs: I love you as much as I would grieve if you died.
With my lost saints - I love thee with the breath,
Smiles, tears of all my life! - and, if God choose,
I shall but love thee better after death.
With my lost saints: she has lost holiness - he is her God now
Better after death: their love transcends mortal life