Chiasmus

‖n. [ NL., fr. Gr. chiasmo`s a placing crosswise, fr. chia`zein. See Chiasm. ] (Rhet.) An inversion of the order of words or phrases, when repeated or subsequently referred to in a sentence; thus, [ 1913 Webster ]

If e'er to bless thy sons
My voice or hands deny,
These hands let useful skill forsake,
This voice in silence die. Dwight. [ 1913 Webster ]