Rhetorical things

chiasmus: A rhetorical or literary figure in which words, grammatical constructions, or concepts are repeated in reverse order, in the same or a modified form; inversion in the second of two parallel forms.

But O, what damned minutes tells he o’er
Who dotes, yet doubts; suspects, yet strong loves.

—Shakespeare, Othello 3.3

antimetabole: the repetition of words or ideas in successive clauses, but in transposed grammatical order.

Ask not what your country can do for you; ask what you can do for your country. –JFK

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Milton, Upon the Circumcision: 
O more exceeding love or law more just?

Just law indeed, but more exceeding love!

Milton, Paradise Lost: 
The law of God exact he shall fulfill
Both by obedience and by love though love
Alone shall fulfill the law…