Speeches in this year's presidential campaign are awash in a rhetorical device called antimetabole, according to an article in Slate.

In this device, the speaker repeats words in successive clauses in reverse grammatical order, as in President Kennedy's "Ask not what your country can do for you; ask what you can do for your country."

I learned about the Slate piece in an "On the Media" segment, which linked to this definition. Slate cited a Wikipedia article about antimetabole, which explains the word's Greek origin. Follow the links above for more examples, and click here for a pronouncing guide.

Sometimes English grammar conventions are confusing for those who learn English as a second language. I found a funny video that explains the order of adjectives.