For a scientific foundation of the Mind humanities that study the practical Mind in a practical orientation, it is necessary for them first of all to determine the structure, the function and the way of operation of the mind. While the task itself is already a serious and very important job, thereafter there is another task to diagnose diseases and health of mental function, by being able to determine the impact of the mind, which he produced in the framework of internal and external surrounding world conditions. Finally, Mind humanities, trying to resolve the such diseases and to make the mind still healthier, need to develop appropriate methods and techniques that must be used to treat them. Theses are all the sorts of aspects or tasks that must be fulfilled for an establishment of Mind humanities. To achieve these tasks, Mind humanities must do first of all the things like searching, finding, interpreting and reconstructing the already existing major materials of all times dealing theoretically and practically with mind. Finally Mind humanities must can design their own conceptual model of the mind. One example is here. It seems to me that the psychosynthesis of Roberto Assasioli would be a good theory suitable for such a purpose. In this article I will describe his theory of psychosynthesis in its core reconstructively and then evaluate critically in connection with the foundational issue of Mind humanites. The discussion is centered on questions of the structure, the function and the way of operation of the mind, as long as it is an urgent task for Mind humanites first and foremost to answer those questions. In my estimation, Mind humanites can learn a great deal from the mind-model that Assagioli had submitted.