Metaphor and humor can both be useful in achieving a deeper understanding.
Metaphor is seeing similarities in different parts of reality. By seeing these similarities it then becomes possible to see the reality that underlies the parts. When Salvador Dali draws correspondences between the behind of a rhinoceros and a rose, he doesn't just see these similarities; he also sees what is under these similarities. And as someone who has in the past used extended metaphor, I can vouch for the usefulness of this approach.
In 1995, when I was 19 years old, I was posting to the Internet as "DR. ROCKET" and was using metaphor related to this all the time. Soon everything became one or another variation on that theme. My apartment became a silo; my girlfriend became Rocket Queen; the cat became the Rocket Catmonster. I got so into it that I was spouting out metaphors all over the place and got quite good at it, and some people described my writing at the time as being transcendent. The real meaning of this term in the way that it was applied is that I was getting, through metaphor - through comparing different things that existed - at a deeper meaning that is common to those different things: A reality of which all those things are a part and that, through extended comparisons, becomes manifest in one's writing.
With humor, there is also a way to get at deeper meaning. While metaphor is seeing the similarities in things, humor is the sense of where they differ. Humor is the sense of the absurd. When Patch Adams goes into a children's hospital ward and uses their toilets as if they were shoes, the funny part is the absurdity of a grown man doing such a thing. As someone who's used humor to the point of having people ask me if I was a comedian, I have also found it useful for more things than just laughs.
When a lady who's lived till she was over 100 years old was asked how she did it, she said, "Pickles and a good sense of humor." I've come to believe that the latter part was not only useful because laughter is good for one's health; it's also something that can inform understanding. And any number of humorists - Charlie Chaplin, Bill Maher, David Barry, Dennis Miller, Chris Farley - developed very deep understanding of things that have extended far beyond the demands of their profession.
In the mechanism, metaphor and humor are opposites of one another. Metaphor sees into reality through finding similarities among things that are not usually compared; humor sees into reality through finding differences and absurdities in things that are taken for granted. While metaphor compares and then sees the commonality between things that are apparently unrelated and challenges the mind to expand understanding to see into the underlying reality, humor also challenges the mind to expand its understanding to see the absurdities in what is regarded conventional and to go past the conventional to achieve a deeper insight into the workings of the universe that the conventional provides.
Both humor and metaphor can therefore be useful guides toward deeper understanding; and it is this that is the true virtue of both.