On Power (De Potentia) is one of Aquinas's "Disputed Questions" (a systematic series of discussions of specific theological topics). It is a text which anyone with a serious interest in Aquinas's thinking will need to read. There is, however, no English translation of the De Potentia currently in print. A translation was published in 1932 under the auspices of the English Dominicans, but is now only available on a CD of translations of Aquineas coming from the InteLex Corporation. A new translation in book form is therefore highly desirable. However, the De Potentia is a very long work indeed (the 1932 translation fills three volumes), and a full translation would be a difficult publishing proposition as well as a challenge to any translator. Recognizing this fact, while wishing to make a solid English version of the De Potentia available, Fr. Richard Regan has produced this abridgement, which passes over some of the full text while retaining what seems most important when it comes to following the flow of Aquinas's thought.