President Kennedy makes frequent use of parallelism and antithesis in his Inaugural Address. How do parallelism and antithesis help him make his points?
When two opposites are introduced in the same sentence for contrasting effect, this is called an "antithesis." These are generally popular sayings containing wisdom. Examples include sayings such as "Many are called, but few are chosen" and "Ask not what your country can do for you, ask what you can do for your country." The last example is a famous quote uttered by President John F. Kennedy during a speech.
Antithesis means opposite, but perhaps on a larger scale. If you say that a woman just told you her beliefs and they were the opposite of what you believe, that is one thing, but if you say they were the very antithesis of everything you believe and know to be true... that is something else. Similar, but more dramatic perhaps. :)