Here we must take account of one of St. Thomas's conceptual distinctions, which at first seems like unnecessary caviling. It is the distinction between "uncreated" and "created" happiness. We have here something which, while not at all obvious, is nevertheless fraught with consequences for our whole feeling about life. Namely, this: what does indeed make us happy is the infinite and uncreated richness of God; but participation in this, happiness itself, is entirely a "creatural" reality governed from within by our humanity; it is not something that descends overwhelmingly upon us from outside. That is, it is not only something that happens to us; we ourselves are intensely active participants in our own happiness. Beatitude - Thomas is saying - cannot possibly be conceived as a merely objective condition of sheer existence. It is not a mere quality, not pure passivity, not simply a feeling. It is something that takes place in the alert core of the mind... Happiness is an act and an activity of the soul.
Creator of all things, true source of light and wisdom, origin of all being, graciously let a ray of your light penetrate the darkness of my understanding. Take from me the double darkness in which I have been born, an obscurity of sin and ignorance. Give me a keen understanding, a retentive memory, and the ability to grasp things correctly and fundamentally. Grant me the talent of being exact in my explanations and the ability to express myself with thoroughness and charm. Point out the beginning, direct the progress, and help in the completion.
The fact is, the great intellectuals of the western religious tradition from Augustine to Aquinas and Peter Abelard became philosophically dominant. The intellectual tradition was preserved. The great intellectuals of the Islamic tradition like Averroes and Avicenna became heretics whose influence disappeared under the weight of rote preaching and practice. Islam as a result has a moral code, a legalistic system of right and wrong, but no evolved ethical tradition.
For the believer in divine creation, the open question of the Mystery of Being is like an open wound. It stings and gapes, and the believer cannot rest till it be healed up, closed up, smeared with the soothing balm of an answer, even if his doctrine be a sophisticated one like Aquinas's or that of the latest Liberal Protestant theologian.
The attempt to understand morality in the legalistic terms of a natural law is ancient but is now mostly associated with the formulation given it by Thomas Aquinas in the late thirteenth century. All earlier natural law is commonly seen as leading up to Aquinas’s paradigmatic version, whereas later natural law is understood as deriving from it.