The body undergoes an uninterrupted change during its whole lifetime. This change is toward physical growth and development until a certain period becoming stronger and more perfect.
However this growth stops at a certain point and decay begins. Unlike these changes first toward growth and development and then toward decay and death a man can continuously grow in learning and he can also continuously develop or may decay spiritually and intellectually or while developing or decaying he may stop at any point and then change his direction. That means his moral spiritual and intellectual education does not depend at all on his bodily changes. Also the moral spiritual and intellectual differences among human beings have nothing to do with their physical structure. Although every human being is composed of the same substantial physical or material elements what is it that causes the moral and intellectual differences among them? What part of man receives moral and intellectual education and what part of him is trained physically? Does physical training bear any relation to learning and moral and intellectual education? Can we say that the more a man is trained physically and the more developed bodily the more he becomes developed in learning and morality? If we cannot say so and if physical training or development has nothing to do with one’s scientific moral and intellectual level why should we not accept the existence of the spirit and how could we attribute learning and moral and intellectual education to some biochemical processes in the brain? Are those processes swifter in some than in others? Or so are some more developed intellectually because those processes are more swift or the processes are more swift because some study and are developed intellectually more? Also what relation do those processes have with one’s spiritual and moral education and development? How can we explain the differences his regular worship makes on one’s face? Why are the faces of the believers more radiant than those of unbelievers and sinful ones?

Also we have mentioned that man undergoes a continuous physical change first toward growth and then toward decay and the cells of his body are renewed every six-month. But he does not change in parallel to those changes in character and morality and thinking. Again how can we explain other than by admitting the existence of the spirit as the center of thinking feeling making choices and decisions and learning the differences of opinion and preference among human beings and the differences in characters?