Purpose of Paradox
After examining the examples from works of literature, one will see that a paradox is not just a witty or amusing statement. Paradoxes have serious implications in the world of literature, because they make statements that often sum up the the main ideas of the work.
What is the purpose of using such a statement then, instead of just forthrightly stating the work's intent?
One reason is that to do so would be boring. It is much more interesting for a reader to carve out the meaning, than to have it fed to them on a silver platter.
Furthermore, summing up the totality of the work in one statement is more memorable. "I must be cruel to be kind" is a famous statement that has transcended history, whether or not people know where the words originally came from.