An antithesis is a rhetorical device whereby two opposing ideas are put together in the same sentence to achieve a contrasting effect. Mary Wollstonecraft uses antithesis in the opening paragraph of her introduction to A Vindication of the Rights of Woman when she says that
either nature has made a great difference between man and man, or that the civilization which has hitherto taken place in the world has been very partial.
In this passage, Wollstonecraft uses antithesis to highlight one of the book's most important themes: that the most significant differences between men and women are those artificially imposed by civilization. Natural differences between men and women in terms of their respective physical strength are not the main reason why women hold such an inferior position in society. Women have been rendered "weak and wretched," argues Wollstonecraft, by means of artificial control by men. In other words, there is nothing whatsoever in women's nature which makes them fit for a life of subordination. The current lowly position of women is purely a product of society and civilization.