Sonnet 43 by Shakespeare

Shakespeare's Sonnet 43 employs antithesis and paradox to highlight the speaker's yearning for his beloved and sadness in (most likely) his absence, and confusion about the situation described in the previous three sonnets.

Paraphrase
I see best when my eyes are closed. All day I am forced to look on what I do not care about; only at night, when my dreaming eyes see you, do I truly see. For even your image (ie, shadow) brightens all the shadows of a dream, and how much brighter you are in daylight, when you may be seen in reality? How much, then, would it delight me to see you in reality, when already your image in my dreams makes them so bright? Until I can see you again, my days are as dark as night because of your absence, and my nights as bright as day because of your sight in my dreams.

Source and analysis
This is one of the poems omitted from the pirated edition of 1640. Gerald Massey notes an analogous poem in Philip Sidney's Astrophil and Stella, 38.

Stephen Booth notes the concentration of antithesis used to convey the impression of a speaker whose emotions have inverted his perception of the world.

Edmond Malone glosses "unrespected" as "unregarded." Line 4 has received a number of broadly similar interpretations. Edward Dowden has "darkly bright" as "illumined, though closed"; he glosses the rest of the line "clearly directed in the darkness." Sidney Lee has the line "guided in the dark by the brightness of your shadow," while George Wyndham prefers "In the dark they heed that on which they are fixed."

In line 11, Edward Capell's emendation of the quarto's "their" to "thy" is now almost universally accepted.

Musical Setting
Sonnet 43 was set to music by Benjamin Britten as part of his Nocturne for Tenor, 7 Obligato Instruments and Strings.