I think everyone agrees that our purpose in life is growth, physical, mental, moral, and spiritual. The purpose of life is to raise the mortal into immortality; to give time and opportunity for the deathless spiritual potency at the core of man's being to develop, grow, unfold into perfection.
Man is a composite being with three elements in his constitution, first a personality that we call by name; second, back of his personality we find a deeper reservoir of consciousness expressed in the ideal desires of the nature; third and lowest of all is the animal consciousness, including the body which is the vehicle for the two higher elements. When we understand this threefold division we can more fully understand St. Paul's description of man as body, soul, and spirit.
It is this higher, ideal nature, the Spiritual Ego, which reincarnates. The word reincarnation means re-entering a body of flesh. Human reincarnation is one phase of the universal law of evolutionary growth through alternate states of rest and reimbodiment. Re-imbodiment of everything that has life is a habit of Nature. Universes, solar systems, suns, worlds, men, animals and plants, cells, molecules, atoms, all reimbody. This habit of Nature is to me one of the strongest proofs that man reincarnates. The innermost Self of man is a deathless Being, a god, which reclothes itself from age to age in new bodies or vehicles, that it may undergo all possible experiences in the Universe to which it belongs and so reach its own most complete growth and self-expression. Rebirth, then, is the pathway of evolution. It is the method by which Nature progressively draws into growth or unfoldment the limitless capacities latent in all creatures from atoms to gods. The very fact that we intuitively know that there are large reserves of power and possibility within us that are seeking expression; the fact that nearly everyone yearns to develop, to be, that Greater Self which he senses within — this very urge to a larger and fuller life, is our daily witness to Nature's true purpose for man. It is through Reincarnation alone that man can bring out and perfect this hidden wealth of power and capacity. In each life some new phase of character is shaped by environment. New powers and capacities are unfolded from within. Weaknesses, selfishness and other faults are corrected by suffering.
We might ask here why we do not remember our past lives, because it would seem that if we did remember, we should not make so many mistakes. However it is well that we do not remember details of our past lives because we should spend too much time reviewing our mistakes, which would hinder our evolution. Evolution always looks forward, is constructive, builds afresh and on developing patterns. So, instead of remembering our mistakes, we simply carry over the memory of the lesson learned by the experience. Character is memory, genius too is memory; and both these are a result of repetition through life after life of lessons which have been realized and absorbed and have become a permanent part of our nature. Character is the spiritual fabric woven by evolution. It is the only thing we can take out of life when we go; it is what we bring back as our heritage from the past when we return to incarnation on earth.