To attain significance the soul must express its potentialities.

To express its potentialities through a physical form it must secure nutritional protection for that form. And to provide opportunity for other souls to express their potentialities through a physical form, it must exercise the drive for reproduction."

"In their expanded form, the drive for nutrition embraces all means of survival, the drive for reproduction embraces mental creation as well as physical progeny, and the drive for significance embraces the various means of expression.

Every step in evolution on this earth has been in response to one or more of these drives - the drive for nutrition, the drive for reproduction, the drive for significance.

And every step in evolution has been in the direction of attaining greater success in the fulfillment of one or more of these three drives.

In response to these drives the protozoa developed from some simpler form of life, then the sponges developed, then the jelly-fishes, then the flat-worms, then the round-worms, then the wheel-worms, then the bryozoa, then the star-fishes, then the worms, then the crayfish, then the oysters, then the vertebrate animals, and finally the human.