We've all heard a politician on their soapbox, pushing for some policy change or cleaning up after a scandal. Some will cut out a sharp point, while others leave the audience in bewilderment. You can often thank - or blame - the use of metaphor for the outcome of a speech.

Most often, the problem comes down to either poorly chosen metaphors, or "mixed" metaphors. A mixed metaphor is one in which half of the statement refers to something metaphorically that doesn't match the other half. Here's a hilarious example by cartoon superstar Homer Simpson:

-----"These people are the glue that holds together the gears of our society."-----

The metaphors "glue" and "holds together" aren't very appropriate when imagining gears. Gears are used in situations where there is movement, while glue is used to prevent movement. A sentence that puts these completely incompatible metaphors together is funny because it is perfectly ineffective but easily visualized.

Had Homer said "...the glue that holds together the pieces of society", it would've been an effective metaphor and statement, but not at all funny. This is because "glue", "holds together" and "pieces" are all metaphors belonging to the same metaphor system, one that, in this case, suggests that society is a solid construct of many parts.

But had Homer used half of the metaphors from "glue" and the other half from, say, "chemistry", many listeners would not have found humor at all, having too little knowledge from chemistry to find the metaphors reachable. If you want people to find what you are pointing to in a metaphor, make sure it's reachable to them.

Take great care in selecting every metaphor you are using in a sentence, paragraph or entire work. Do the metaphors you use work well together? Do they create an image in the reader's mind that is consistent and easily visualized? Will most readers identify with the metaphor systems you refer to?

Points to remember when building effective metaphors:

1) Make your metaphors consistent.
2) Make sure your metaphor is easy to visualize.
3) Make sure your metaphor is reachable.

The metaphor has been held in high regard by many cultures for thousands of years. Its use as a tool in the right hands can build imagery that will stand the test of time. In the wrong hands, the metaphor will make one's words fall flat, becoming soon forgotten. Build your metaphors to last - craft them carefully, deliberately and reachably.

John D. Casnig is a writer and publisher in Kingston, Ontario, Canada. His current focus is on the metaphor and its use as a teaching and learning tool. His online arts magazine, Jaywalker Magazine of the Arts, features some of his work, as well as works from other people in his region.