The study of thought and of the natures of things.
Psychology /
Christian Anthropology
The study of man's nature, of his capacities, his interior life, the relationship between his flesh, or animal nature, and his spiritual center where God would be at home.
The curriculum essay, A Curriculum for the Culture of Life, is a philosophical dicussion of how to assemble a curriculum based on Catholic philosophy and Catholic anthropology/ psychology. Since education is personal and intellectual formation, it reflects the actual psychology of its shapers in any generation.
Perhaps the most unifying of all disciplines: music is the union of the harmony in sound, perfection in mathematics, poetry in language, and beauty in the physical human voice, which was made for the expression of love. A spiritually inspired (and theologically accurate) hymn to the Creator partakes of even greater unities. Choral singing may even contribute to civics!
There are a thousand other sub-disciplines and cross-disciplines. They are not less important for not being listed, for each represents a unique vocation of engagement to which one may be called in the manifold plan of God. But these are the foundations, essential to a full Christian engagement with the world. Each represents a specific aspect of the formation of the interior life.