From the book "Soulcraft", by Bill Plotkin:
"Inside a caterpillar's body are clusters of cells called "imaginal buds". (Imaginal refers to the adult phase of the caterpillar's life, i.e. the Butterfly Phase.) The Imaginal Buds contain the idealized image, the blueprint, for growing a butterfly. While the caterpillar goes about its earth-crawling business, these cells, deep inside, are imagining flight.
The caterpillar's immune system believes these cells are foreign and tries to destroy them, not unlike the way uninitiated human egos and our egocentric cultures often try to destroy our own evolutional elements. It's as if the caterpillar doesn't realize its destiny. (It's no coincidence the Greek word for butterfly is "soul".) Once in the cocoon, the buds link up, the caterpillar's immune system breaks down, and its body literally disintegrates. The buds then build a butterfly from the fluid contents of the cocoon.
Once you've arrived in your own cocoon, you come to understand what the butterfly knows: upon forming your cocoon, you prepare to die in order for something new to be born."