As two of the many great scholastics who contributed to Christian theology and philosophy in the 12th and 13th centuries, Thomas Aquinas and Bonaventure stand out among the pack. Many Christians are already aware of the monumental effect that Aquinas has had on Christian theology, such as providing logical proofs for the existence of God and explaining God’s relationship with creation (Irvin and Sunquist 431, 432). Yet Bonaventure also had a key role in defining God as an omnipresent, omniscient, omnipotent being, as well as exploring how creation comes to know God.
Because Bonaventure cut his teeth on Aquinas’ teaching, both were bound to have shared approaches to defining God and other theological topics, though with a few differences too. When reading Aquinas’ and Bonaventure’s individual works on theology, they both use similar terms to describe God’s attributes. In the Summa Theologiae, Aquinas repeatedly equates God to words such as existence, essence, nature, and substance.
Aquinas’ bottom-line point is that God *is* existence itself, essence itself, and nature itself (Article 3, 4). He is also substance itself, although not as the genus of substance as Aquinas explains: “The word substance signifies not only what exists of itself – for existence itself cannot be a genus…it also signifies an essence that has the property of existing in this way – namely of existence itself” (Article 5). What is fascinating about this definition — despite having to read it several times to get the point – is Aquinas almost teeters on circular reasoning; but then he weaves in enough logic to avoid an all-out fallacy such as “existence exists because it’s existence.”
For example, Aquinas relates existence to essence in this way: “Now it is impossible for a thing’s existence to be caused by its essential constituent principles, for nothing can be the sufficient cause of its own existence, if its existence is caused. Therefore that thing, whose existence differs from its essence, must have its existences caused by another. But this cannot be true of God; because we call God the first efficient cause. Therefore it is impossible that in God His existence should differ from his essence” (Aquinas Article 5).
Like Aquinas, Bonaventure also equates God to all encompassing words that capture cosmic realities. In his work, The Journey of the Mind to God, Bonaventure uses the word being similarly to how Aquinas uses existence, essence, and so on. For Bonaventure, “If God is the name of the primary, eternal, most simple, most actual, most perfect being, it is impossible that He be thought of as non-being….for being itself is first and last, is eternal and yet most present…is most highly one and yet all inclusive” (Ch. 5, par. 6, 7).
Now, while Aquinas and Bonaventure held somewhat similar definitions of God, they did not align so much on how humans come to know God. According to Aquinas, the natural world and the supernatural together give a fuller picture of theological reality. This starts with the simple fact that most human beings have multiple sensory mechanisms: sight, hearing, touch etc. The senses cause the mind to produce images, form ideas from them, and then use logic to connect these thoughts to reality – or at least a reality that fits with the natural world and sound reasoning (Irvin and Sunquist 431).
Aquinas’ proofs for the existence of God are one example of using logic and reason to connect the natural world with supernatural ideas. However, Aquinas understands the limitations with this; therefore, he argues that metaphors and analogies can help bridge gaps between the natural and supernatural, though they do not provide be-all, end-all explanations.
Which is why Aquinas ultimately points to revelation as the glue that binds logic and reason to complex theological topics (Irvin and Sunquist). Aquinas states this as follows, “But the end must first be known by men who are to direct their thoughts and actions to the end. Hence it was necessary for the salvation of man that certain truths which exceed human reason should be made known to him by divine revelation” (Aquinas Article 3).
Bonaventure, on the other hand, stayed with a more mystical approach to knowing God. For one, and unlike his contemporaries, Bonaventure did not put Aristotelian philosophy on the same plane as Augustine. As such, Bonaventure did not believe in using reason as a starting point to know God (Irvin and Sunquist (443): “But just as the eye intent upon the various differences of the colors does not see the light by which it sees the other things and, if it sees it, does not notice it, so the mind’s eye, intent upon particular and universal beings, does not notice Being itself” (Bonaventure ch. 5, par. 4).
Aside from their differences on how humans develop an understanding of God, Aquinas and Bonaventure also shared a similar belief in God’s unity and its effect on creation. By referring to John 17:3, as well as showing that this unity begins with the consubstantial relationship between God, Jesus, and the Holy Spirit, Bonaventure writes, “For we should wonder not only at the essential and personal traits of God in themselves, but also in comparison with the superwonderful union of God and man in the unity of Christ’s person (Bonaventure Ch. 6, par. 3, 4).
Similarly, Aquinas sees the triune God as a consubstantial relationship, and where each of the three persons mutually define one another. Furthermore, Aquinas sees grace as central to God’s relationship with creation and through the mutual relationship between Father, Son, and Holy Spirt (Irvin and Sunquist 431).
Where Aquinas and Bonaventure differ on this is not so clear cut. Both have a ubiquitous, rather almost ethereal understanding of God’s attributes; both have a similar view of the triune God’s connection with creation; and the selected writings from Aquinas do not exactly dive deep into this subject, other than to establish God’s attributes and refute the misunderstandings about them. And at the risk of making excuses, I think the part of the question about “unity” needs some clarification 😁
Works Cited
Irvin, Dale T., and Scott W. Sunquist. History of the World Christian Movement: Earliest Christianity to 1453. Maryknoll: Orbis Books, 2001.
St. Bonaventure. The Journey of the Mind to God, Prologue. http://www.ccel.org/ccel/bonaventure/mindsroad.v.html
St. Bonaventure, The Journey of the Mind to God, Chapters 5 and 6. http://www.ccel.org/ccel/bonaventure/mindsroad.x.html
St. Thomas Aquinas. Summa Theologica, 1a.1.1-10. http://www.newadvent.org/summa/1001.htm
St. Thomas Aquinas. Summa Theologica,1a.3.1–5. http://www.newadvent.org/summa/1003.htm