The ultimate purpose or True Will of a tree is to seek light and nutrients for sustenance and to grow. A fire's purpose is to consume fuel and transform it to ash. It is more difficult to find the ultimate purpose of any given human, because we have the added complication of a frontal lobe, and therefore conscious decision-based thought. This is an issue of importance in this day and age, when population growth and other problems of impact are threatening the health and stability of not only human life, but all other forms of terrestrial life as well. The concept of True Will ties into the question of reincarnation.
Time is of a spiraling, non-linear nature.
In the organic vein of thought, the building blocks of our body are eternal. It is my belief that DNA carries memories and encoding. We are born into each of our specific bodies to integrate the information in our cells with our eternal selves. In the philosophy of Thelema everything is a part of nature. Injustice and abuse are only possible when we are not acting with consciousness, or we are acting consciously outside the laws of nature.