Physically he is not born in full stature but passes through consecutive stages of fetus, infant, childhood, youth, maturity and old age. Suppose he had the power to remain young throughout his life. He then would not understand the meaning of old age and could not believe it existed. If he could not realize the condition of old age, he would not know that he was young. He would not know the difference between young and old without experiencing the old.
Death is the absence of life.
Briefly, the journey of the soul is necessary. The pathway of life is the road which leads to divine knowledge and attainment. Without training and guidance the soul could never progress beyond the conditions of its lower nature, which is ignorant and defective.