In a Charlotte Mason education, the so-called "extras" are not really extra. They are what make life rich. The poetry, the music, the handicrafts, the nature walks are all part of the "science of relations"...the relationships children are forming with the world around them. Yes, the core subjects of reading and math are essential, but not for any utilitarian reason. Reading is a skill that opens the door to even more relationships...with people from history, with places far away, with ideas. And yes, math is about relationships, too.
"a system of education should have for its aim, not the mastery of certain 'subjects,' but the establishment of these relations in as many directions as circumstances will allow." (vol. 3, p.88)