Thomas Aquinas

===Nature of sin===
Following [[Augustine of Hippo]], Thomas defines [[sin]] as "a word, deed, or desire, contrary to the [[Divine law|eternal law]]."<ref>{{Cite book |author=Thomas Aquinas |title=Summa Theologica |volume=II-I |chapter=Question 71, Article 6 |access-date=17 January 2010 |chapter-url=http://www.newadvent.org/summa/2071.htm#article6 |via=newadvent.org}}</ref> It is important to note the analogous nature of law in Thomas's legal philosophy. Natural law is an instance or instantiation of eternal law. Because natural law is what human beings determine according to their own nature (as rational beings), disobeying reason is disobeying natural law and eternal law. Thus eternal law is logically prior to reception of either "natural law" (that determined by reason) or "divine law" (that found in the Old and New Testaments). In other words, God's will extends to both reason and revelation. Sin is abrogating either one's own reason, on the one hand, or revelation on the other, and is synonymous with "evil" ([[privation]] of good, or ''[[privatio boni]]''<ref>{{cite book |author=Thomas Aquinas |title=Summa Theologica |volume=II-I |chapter=Question 75, Article 1 |quote=For evil is the absence of the good, which is natural and due to a thing. |chapter-url=http://www.newadvent.org/summa/2075.htm#article1}}</ref>). Thomas, like all Scholastics, generally argued that the findings of reason and data of revelation cannot conflict, so both are a guide to God's will for human beings.