UPDATE: The eBooks of the Arts of Liberty Project are currently available free of charge.
The Arts of Liberty Project provides six eBooks, covering five of the liberal arts: logic, rhetoric, arithmetic, geometry, and astronomy. They are available free of charge, both for self-study and for use in the classroom. Please do give credit to the Arts of Liberty Project. If you are interested in partnering with the Arts of Liberty project to produce an eBook that would cover the two missing liberal arts (grammar and music), please contact us at firstname.lastname@example.org.
Thomas More’s Utopia and Francis Bacon’s New Atlantis are available for free, as well, courtesy of the Center for Thomas More Studies.