Although St. Thomas was primarily a Christian theologian, we are interested here in his philosophical vision. It must be pointed out that for St. Thomas there exists a fundamental harmony between human thought (reason) and faith. Both come from the same source, God. Philosophy has its own authority and autonomy. In working out his philosophical vision St. Thomas repeated time and again that the human intellect is capable of attaining at truth on its own, and that this is possible even without the aid of grace. Here he pointed out the Greek Thinkers as an example.
For St. Thomas philosophy is necessary since it is the common ground on which all people willing to seek the truth can meet, even if they differ insofar as their religious faith in revealed scriptures is concerned.1
The primary concern of St. Thomas was always one: to show the truth. Here is the root of his extraordinary universalism, when it comes to collecting true insights from any thinker whatsoever whether among his predecessors or contemporaries. Although Aristotle remained for Thomas always 'the Philosopher,' he had to modify Aristotelian views considerably, and elements of Platonism, Neo-Platonism, Arabic and Judaic thought are not lacking within his synthesis, which nevertheless remained thoroughly original.2
Thus, from Aristotle, Aquinas took the basic position of the theory of knowledge and on it he built his moderate realism, within which the ultimate ground of truth is always in realistic experience. The Stagirite provided also the theory of the causal connection of beings. When it comes to the theory of finality in the universe, Aquinas utilized the analysis of change done so well by Aristotle and his notion of immanent finality of beings composed of matter and form. In this regard, however, he had to modify Aristotle on many essential points, especially when it comes to consider the relationship between God and the universe. For Thomas, God is the Creator–the Efficient Cause of all reality that is not God. He is also the Ultimate Final Cause of the universe. It is impossible to know the First Cause without at the same time knowing the First End.3 For St. Thomas all beings are most intimately dependent in their whole reality on God's causality: in their existence, in their operations, in their structure and in their finality. But, most importantly, finality in Thomas' thought is ultimately grounded in the Divine Intelligence operative in the universe as well as directing all towards God, as the Ultimate Final End. Here Thomas went-as we shall show later in what follows–far beyond Aristotle. The relationship between the God of Thomas Aquinas and the universe is far richer and more intimate than any ancient thinker could imagine. The essence of this relationship can be briefly, in a condensed version, expressed as: Creator-creature. The basic condition of every finite is defined by creatureliness. God's position is best expressed in this respect by the two letters of the Greek alphabet: alpha and omega.
There is in Thomas a considerable amount of Plato's thought. Two elements especially are of Platonic origin: the idea of participation, and the idea of forms as models of all creatures. Both positions are deeply transformed: although the ideas are models of all creatures, they are in God's mind in Thomas' philosophy, as God sees his Essence as imitable in finite modes ad extra. They are not, as in Plato, independent, subsistent entities on their own. As for participation, Thomas considers it on the plane of being primarily:4 each finite being insofar as it is a limited act of existence, and to that degree, participates in the perfection of Existence Itself in an analogical mode. The last remark is to be kept in mind always: being is intrinsically analogical for Thomas. God as an Intelligent Planner of the Whole Universe may also be of Platonic parentage (The Demiurge of Plato's Timaeus).
In many points Thomas agreed with Augustine, insofar as the doctrine about God is concerned both Aristotle and St. Augustine were the source, and moreover the Christian Neo-Platonist Pseudo-Denys, the early scholastics like St. Anselm and St. Bernard. It is hardly necessary to mention that the one who influenced St. Thomas the most insofar as the Aristotelianism of Aquinas goes, was his master Albert the Great.
Without falling into crude pantheism, St. Thomas incorporated into his synthesis the Plotinian idea of a hierarchical universe in which different layers of being are related to each other within the scheme of a ladder, from the least perfect to the highest. The section below man is pictured by Thomas primarily according to Aristotle, but the upper part, from man up, is predominantly neo-Platonic. Utilizing those principles, Thomas remained always within the limits of Christian philosophy; pantheism is completely alien to him. One of the fundamental principles pervading his whole metaphysical vision is the analogy of being.9 Within the emanationist system of Plotinus, in which everything proceeds with necessity – an idea not acceptable to the Christian understanding of the God/creature relationship–nevertheless all is ordered and pervaded by Intelligence. The principle of the sensible world realized according to order in space and matter “can only be absolutely fixed intellectual order, containing in an eternal form and accessible to pure intelligence the relationships and harmonies which are perceived in the sensible world.”10 In the Plotinian system, Intelligence–the first hypostasis–is the central hypostasis. It is above all an order, an intelligible world. But the ultimate ground of order is the Unity, the One. The One of Plotinus is a reality higher and anterior to the order itself: the One is the 'source' or the 'First.' The One includes all without distinction. St. Thomas could use much of Plotinus and he certainly did. There is a certain primacy of intelligence in the Plotinian system. This element is certainly very clear to Aquinas. However, more detailed discussion of this problem here, would go beyond the purpose of this work.The influence of St. Augustine is visible especially insofar as God's knowledge of this world is concerned, and Augustine's view of the world as created and ordered by seminal reasons: principles of teleological development, intrinsic to beings in which all perfections are potentially present. Those principles are designed by God and 'put' into things by the very fact of creation which is done according to the plan of God's ideas, in God's Intelligence. Those ideas are the exemplars according to which God's creative work is designed. In St. Augustine's own words: “God therefore knew all things which he made before He made them… He knew them that He might make them, not because He had made them.”5 In book XVIII of De Civitate Dei the bishop of Hippo says: “And His wisdom being simply multiple and uniformly multiform, can comprehend all incomprehensible things with such incomprehensible comprehension that whatsoever thing that is new and unlike to all other He should ever please to create, it could not be irregular or unforeseen by him.”6
In the “seminal reasons” (rationes seminales) there is a principle of intrinsic teleological development of all reality: “As in the seed there are invisibly present all the things which in course of time will grow into a tree, so the universe must be conceived…”7 And so, according to Augustine, “God's will diffuses itself through all things by certain perfectly ordered movements of created things, first spiritual, then corporeal, and puts all to the service of the immutable bidding of its purpose…”8 The Platonic ideas are now ideas of God's creative structuring of all reality according to His intelligent design. This idea is obvious in the system of Thomas Aquinas. For him, too, all action for an end is ultimately grounded in God's Intelligence. The Christian Platonism of Augustine was primarily Christian. As such it could be utilized, to an extent, by St. Thomas.
We must stress emphatically at this point that although St. Thomas used all those elements of other thinkers, and he confesses this openly (see footnote), nevertheless his synthesis is not a mere eclectic conglomeration: as we hope it will appear later in this work, Thomas hardly used any elements of other thinkers without a deep transformation and adaptation within his basic focus of reflection, always present to his mind: the focus on the plane of being as such, the existential plane, on the basis of which all principles flow together to form a thoroughly original and unified vision of the thinker from Aquino.
We presuppose this knowledge in the reader: the existential character of St. Thomas thought. At this point we mention it only, saving a more detailed elaboration of it for one of the following chapters.