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.