The liberal arts are traditionally intended to develop the faculties of the human mind, those powers of intelligence and imagination without which no intellectual work can be accomplished.
The liberal-arts tradition goes back to the medieval curriculum. It consisted of two parts. The first part, trivium, comprised grammar, rhetoric, and logic. It taught the arts of reading and writing, of listening and speaking, and of sound thinking. The other part, the quadrivium, consisted of arithmetic, geometry, astronomy, and music (not audible music, but music conceived as a mathematical science). It taught the arts of observation, calculation, and measurement, how to apprehend the quantitative aspect of things. Nowadays, of course, we would add many more sciences, natural and social.