The development of natural law is one of the most influential parts of Thomist philosophy. Aquinas says that "law of nature is nothing other than the light of the intellect planted in us by God, by which we know what should be done and what should be avoided. God gave this light and this law in creation... For no one is ignorant that what he would not like to be done to himself he should not do to others, and similar norms." This reflects Paul the Apostle's argument in Romans 2:15, that the "work of the law written in [the Gentiles' hearts, their conscience bearing witness to them."