Editors Note: The following is a discussion of Aquinas' The Commandments of God. All quotations are from Trans. Laurence Shapcote. Burns Oates and Waterhourne, Ltd: London.
One of the interesting facets of the article in question has been dealing with the idea of sin in Aquinas’ work. One might argue as was done in the first class session that it is the issue of sin that provided the impetus for much of Aquinas’ work. As a priest training priests for the work of ministry, Aquinas was concerned to train them in how to deal with the sin issues of their parishioners. In a world defined by the sacraments, misuse and misunderstanding of the sacrament of confession incited Aquinas to teach rightly what it meant to live rightly. With this in mind, it seemed odd to hit the discussion of sin only in the last section of the work. However it was this section that defines and explains everything that came before. A careful evaluation, then, of Aquinas’ views on sin will work to explain his discussion of the Decalogue.
In the section of Tenth (Ninth) Commandment, Aquinas described sin as “the corruption which succeeded the Fall” in which no one “has been immune from the concupiscence” (86). In this sense Aquinas defined sin as that innate, inner inclination to perform an act of sin, be it mortal or venial. A mortal sin was that which completely cut off the believer from the grace of God. It was considered mortal in that if one were to die without having confessed and found absolution, one was endangered of hellfire. A venial sin, then, was that which only partially cut one off from grace. Sin was that which cut off relationship with God and left the person in mortal danger.
Aquinas, then defined sin as acting in a certain way, and following a certain track. Sin, then, works as it “overcomes the reason.” The corruption of sin overpowers the reasoning of the person who as the Apostle Paul. Aquinas defined the way of this act in a multi-step process. First the corruption of sin reigns in the body as the believer gives place to the lusts of sin in their heart (which is equivalent to the passions). This inner inclination first worked its way out in words which express these inner inclinations. These words then turn into actions as the members of the body follow the heart.
This inclination to sin must be combated by the life of the believer. By thinking rightly and ordering one’s life according the believer works in conjunction with the grace of God though Christ working in the power of the Spirit. The base of this right life can be found in the threefold knowledge granted by God in the creed (what to believe), the Lord’s Prayer (what to desire), and the Law (what to do) (1). It was in this way that Aquinas could refer to the law as an “intellectual light instilled in us by God” (1).
Yet just as he described it in his Summa, there are varied kinds of law given which worked on many levels. The highest of which was the Law of Christ which provided both the law and the ability to follow this law. In this way the believer is able to live a life that entails rightness of heart, soul, mind, and strength. In his definition, the heart stands for rightness in intent; the soul means that rightness of will; mind was rightness of understanding; and last strength stands for the ability to perform it (16-17). As the believer worked through this way, Aquinas saw a group of people committed to a life which would receive grace from God, consider the greatness of His gifts, renounce the world, and avoid sin (14-15). As this process would work its way out, the person following Aquinas would become a monk par excellence and in doing so renew the church so loved by Aquinas.