What the human nature is like can be judged by examining the behaviours common to all people and their creations, for example religion. The human nature is unchangeable . However, the forms change, through which it manifests it self in various periods of the development of humanity. In people's religious behaviour, for example, there is manifested something which is the permanent source of every religion and is inherent in human nature. The religious forms, beliefs, rites, institutions etc., in which it manifests itself, change but, itself, it remains the permanent element of the human soul.
Rationality constitutes the essence of humanity.
There exist, however, such spheres of human behaviour which indicate that the human nature cannot be described only in the rational categories. Constany frequently writes about it. I will cite two quotations here. Ici, comme partout, on apercoit la trace des diverses impulsions qui se partagent cet etre a la fois egoiste, raissoneur et moral. These forms are not only stricte religious ones.