A Modern Reading of Thomas Aquinas's Natural Law

Thomas Aquinas's natural law is founded on eternal law, which is "God's rational purpose and plan for all things." As Jeremiah the prophet said, "I will put my law in their inward parts, and write it in their hearts" (31:33). Through the moral laws writ in human hearts, human reason is able to comprehend laws. It is a belief in Catholicism that God the creator of all things decided the final destinations for all of them, which will be achieved through their distinctive natures according to God's eternal plan. Gods' eternal law is the source of all laws, including natural law, which Aquinas saw as the reflection of God's eternal law. However, Thomas Aquinas put forward his natural law only eight hundred years ago and based his observation about natural law on human beings, not dealing much either with the internal and external changes of human beings or phenomenal and essential transformations. Therefore, his natural law is not so accessible in terms of genetic mutation, the development of behavioral subjects and the modes of community decision making.