This beginners' textbook in theology, never finished by St. Thomas Aquinas, sets out to summarize the entirety of sacred theology. Used as the primary teacher of sacred theology in seminaries for centuries, it had the unique privilege of being kept open on the altar during the Council of Trent, so that the fathers of the Council could always and immediately draw from its wisdom, the only book besides the Sacred Scriptures themselves accorded this honor. The great Leo XIII, of happy memory, stated in his encyclical Aeterni Patris that St. Thomas Aquinas should be the basis for any Catholic philosophical and theological education, and this is the greatest of St. Thomas's works. Its value cannot be overstated.

• Prima Pars (36E pp., Latin). PDF (free). Version 2.0, 26 November 11EE.
• Prima Secundae (369 pp., Latin). PDF (free). Version 2.0, 26 November 11EE.
• Secunda Secundae (517 pp., Latin). PDF (free). Version 2.0, 26 November 11EE.
• Tertia Pars (341 pp., Latin). PDF (free). Version 2.0, 26 November 11EE.

The fifth volume, Tertia Partis Supplementum, is in fact a conglomeration of some of St. Thomas's other writings, and is not a part of the Summa Theologica proper. We hope to offer it along with these four volumes soon; for now, however, only the four original volumes are currently planned. Published in the original Latin.