From the moment the soul leaves the body and arrives in the Heavenly World, its evolution is spiritual, and that evolution is: The approaching unto God.
In the physical creation, evolution is from one degree of perfection to another. The mineral passes with its mineral perfections to the vegetable; the vegetable, with its perfections, passes to the animal world, and so on to that of humanity. This world is full of seeming contradictions; in each of these kingdoms (mineral, vegetable and animal) life exists in its degree; though when compared to the life in a man, the earth appears to be dead, yet she, too, lives and has a life of her own. In this world things live and die, and live again in other forms of life, but in the world of the spirit it is quite otherwise.
The soul does not evolve from degree to degree as a law—it only evolves nearer to God, by the Mercy and Bounty of God.
- ‘Abdu’l-Baha (From a talk, November 3, 1911, Paris; ‘Paris Talks’)