Here’s an English translation of a great catechism written by St. Thomas Aquinas, a 13th century Dominican friar, saint and doctor of the Church:
Aquinas, St. Thomas. The Catechetical Instructions of St. Thomas Aquinas. Translated by Joseph B. Collins, S.S., D.D., PhD., Introduction by Rudolph Bandas, PhD., S.T.D. et M., New York, Joseph F. Wagner, Inc., 1939.
The original work of St. Thomas predates the Roman Catechism by three centuries but follows the same four-fold structure: the Creed, the Sacraments, the Commandments, and the Lord’s Prayer. St. Thomas nearly always includes reasons for each article, sacrament, commandment or petition – reasons that are often (and unfortunately) missing from the Catechism of the Catholic Church.
An online version is provided by Catholic apologist Jimmy Akin here.
And here is a downloadable PDF of the entire work:
A copy of the original translation by Fr. Collins may be found here.
