Thomas Aquinas made a major contribution to Christian theology, yet without intending to take anything away from his outstanding and unique contribution, it is nevertheless possible to see how much the thoughts and writings of Augustine eight hundred years previously gave Aquinas both a huge impetus and a huge amount of resource material.
Thomas Aquinas lived from about the year 1225 until the year 1274. Over eight hundred years before then, Augustine had become the predominant patristic authority for the Western churches, often being called as the 'father of the Christian Church of the West. Until Thomas Aquinas gave Christian theology the great benefit of his distinct sense of organisation and order, the works of Augustine were the major theological resource of the church in the West.'
When compared to Augustine, Aquinas had time on his side, in two senses of that word. Firstly, he had time to study and write in a methodical manner, for he was an academic by profession. On the other hand, Augustine very much taught himself theologically, and was primarily an active leader of a local church who was only able to undertake scholarship as a secondary pursuit.
Aquinas was fortunate in having had academic training and the benefit of a scholarly existence in which methodically to prepare his one major work, the Summa Theologica (a "Theological Summary" of the Christian Faith). Secondly, the other time advantage of Aquinas was that, in the eight hundred years since the era of Augustine, the philosophical writings of Aristotle had been brought back from the East by the Crusaders. This allowed Aquinas to adopt an Aristotelian foundation, which suited Christian theology better than the philosophical foundation of Plato that Augustine had had to use. And, of course, Aquinas had the advantage of the availability of the extensive - even if un-coordinated - foundational work scattered throughout many of the writings of Augustine. What Aquinas achieved in his Summa Theologica was brilliantly simple in its concept (not to deny that it would have taken a genius to have first noticed it), yet was hugely profound in its implications.
Another difference between Augustine and Aquinas was the nature of their preparation for theology. Augustine was trained in rhetoric, and Aquinas in the intellectual precision of the philosophy of Aristotle. Augustine was an active pastor (the Bishop of Hippo), who preached and wrote to address immediate theological needs that confronted himself, his people or those who wrote to him for theological advice. In contrast, Aquinas was an academic. In writing a Summa Theologica (a summary of Christian theology), he had to be abstract and away from proposing immediate solutions for immediate needs.
Augustine thought about and responded to situations from his background in rhetoric and his active pastoral environment. In effect, writing was perforce the second priority in the life of Augustine the pastoral leader; for Aquinas it was part of his main priority. Rhetoric is the usual method of serious human communication. It uses persuasive devices such as metaphor, contrast, excessive simplification, etc. It is also the language of the Bible. For example, Paul in Romans 5 describes rhetorically the great struggle between grace and nature, and makes death the companion of sin.
The rhetoric of the Bible – especially of Saint Paul as echoed by Augustine – was to have a great influence on Christian theology. It reinforced the pessimistic side of Augustine, and through him Calvin, Luther, Jansen and the Christian fundamentalism in the world today. Rhetoric may be the most potent tool of preaching and communication, but it cannot have the final word in theology. Theology is a discipline of critical (as distinct from rhetorical) thought. It is a technical study in which the calling forth of human emotion is not to be encouraged. Whereas Augustine developed theology in his rhetorical manner to address immediate theological problems by manuscripts, letters and sermons, Aquinas wrote as an academic, and only published his work at leisure after he was fully ready to do so.
The thought of Aquinas was critical rather than rhetorical. His selection of topics to address was not prompted by any immediate need that was brought to his attention, but by his desire to prepare a reasoned and integrated compendium of Christian theology. Without denigrating Augustine, it can be said that Augustine was not trained to be a theologian in the sense that Aquinas was. By analogy, Augustine wrote individual assignments (although some very lengthy ones!), whereas Aquinas wrote an integrated text book. To have expected that Augustine could have been trained that way in his era, however, is an unfair expectation, for the unavailability of the writings of Aristotle in the Western world in the time of Augustine precluded it.
The major work of Thomas Aquinas was his Summa Theologica. In it, he successfully offered an organised intellectual synthesis of reason (then increasingly an emergent force as human learning quickened in Europe) and Faith (which was still being expressed as taught by Augustine over 800 years previously). To accomplish this, Aquinas recognised the precious metal contained in a somewhat unrefined manner amidst the voluminous writings of Augustine. And Aquinas possessed the genius to extract it effectively.
Aquinas sifted through the mountain of thought by Augustine. He adopted the world view of Aristotle (whereas Augustine had followed Plato) and then used his own particular genius to give Christian theology a sure and coherent underpinning on the reasoning of Aristotle (whereas Augustine in his day had been forced to be based on Plato because the works of Aristotle had not been available). Philosophical differences between Plato and Aristotle led the world view of Augustine to be different from that of Aquinas. The focal point of the respective enquiries of Augustine and Aquinas into the theological meaning of human life and of eternal life were thus different, and this allowed a different shading to the consequences they drew from them. Whereas the focus of Augustine was to seek to understand the intelligibility of the universe, Aquinas wanted to understand the intelligibility of the individual human soul. The focus of Augustine was the world; for Aquinas, it was the human individual. Warren Hollister, a scholar of medieval history, claimed that "Augustine ranks with Saint Paul as one of the seminal minds of the Christian church." He ranked Augustine with Thomas Aquinas as one of the two greatest contributors to the theology of the Catholic Church. Augustine and Aquinas are Christian scholars who have no equal to their influence on the church and Western society in successive generations, right to the present." The Church once proclaimed that the theology of Aquinas was to be the primary vehicle for Catholic theological instruction.
It was from the thought of Augustine from whom Aquinas had borrowed more than from any other Christian source outside of the New Testament. In his Summa Theologica, Thomas cited Augustine 2,801 times, and has been called "one of Augustine's greatest interpreters." To Aquinas, Augustine was the primary patristic authority. He wrote Catena aurea ("The Golden Chain," a fourteenth-century title), a monumental collection of glosses by the Church Fathers on each verse of the Gospels. Therein the theology is Thomistic, yet the sources - other than for the Bible - most cited are the writings of Augustine.
Why is not more heard of the theology of Augustine today?
This is because the theology of Thomas Aquinas overlaps it so much, and in whole is a theology that is better polished and expressed. As well, the Counter-Reformation marked the increase of the prestige of Aquinas over that of Augustine in the Western church; that another author could surpass Augustine would have been scarcely imaginable to scholars as late as perhaps the year 1500.
After approximately that time, although Augustine was still the object of great scholarly veneration, he was no longer taken to be the latest and highest authority on the exposition of church doctrine. With the inevitable change in language and theological terminology since the time of Augustine, his theology is now usually only studied by specialist scholars of the Church Fathers (i.e., the most respected scholars of the early Christian church). It is studied to throw light on the historical development of theology and dogma during the early years of the Church, an era in which Augustine wrote and lived.
Link
From the mind of Augustine to the soul of Aquinas, by John O'Callaghan of Creighton University, in the United States of America. The paper examines a shift in Aquinas from an Augustinian philosophy of mind toward a more full blooded Aristotelian psychology http://www.nd.edu/Departments/Maritain/ti00/ocallagh.htm AN2338