John 12:24
Very truly, I (Jesus) tell you, unless a grain of wheat falls into the earth and dies, it remains just a single grain; but if it dies, it bears much fruit.
If you've not observed metaphor in action before, this passage personifies the idea to the max. The idea of dying to be fruitful may be confusing. What Jesus is getting at is that we can mimic that which we see in nature. Meaning, a seed of grain is planted (as if to die), germinates, sprouts and ultimately bears its "fruit" at harvest. By dying to myself, I turn my life 180 degrees; leave my old self behind, and go on with my new attitude to bear "fruit" among those with whom I am in contact.
The simplicity of the example, a real-life occurrence; yet so very important to the hearer in that, with wheat they live, without it they die; physically. Jesus takes the concept, raises it to a new level of spiritual understanding and offers the hearer a new way of unity resulting in eternal life. And, it still works today.