Antithesis is just a poetical device as a part of Epigram. Epigram is defined in two aspects, Anthesis and Paradox. It is just a device like balanced elements contrasted, where the second part of a sentence contrasts with one first to balance mutual element.
In Antithesis, the capability of a writer looks very fast in twisting his particular sense where so ever he thought about his concern.
> Lucy is no more because she becomes the earthly diurnal course.
> Love is an ideal thing, marriage a real thing.