Summa of the Summa: The Essential Philosophical Passages of St. Thomas Aquinas' Summa Theologica


A number of people have told this reader they are planning to someday read James Joyce’s Ulysses. Others pledge to at least start it. But no one has ever told this reader they plan to finish Saint Thomas’ Aquinas’ Summa Theologica. It is a rare person indeed who would undertake to read it several times, digest it and prepare a compelling edited version.  Peter Kreeft is a philosophy professor at Boston College who has written numerous books on philosophy and theology. This book consists of what Mr. Kreeft has found to be the essential philosophical passages of Saint Thomas Aquinas’ Summa Theologica. Although the original Summa was more than 3000 pages, Mr. Kreeft’s edited version is limited to 532 pages and perhaps one fourth of that consists of the editor’s notes, which are particularly illuminating. He has undertaken to edit and comment on one of the greatest works of one of the greatest Doctors of the Church. Thomas Aquinas was a Dominican friar who lived in the Thirteenth Century. His early studies were at the Benedictine monastery in Monte Cassino, Italy. His family wanted the young scholar to continue his studies there, but he became enchanted with the Dominican order. The Dominicans sent him to study at the University of Paris, where he met Albert the Great, another Doctor of the Church, an honor bestowed on only 36 people. Aquinas studied the works of Socrates, Plato, Aristotle, St. Augustine, St. Albert and other accomplished philosophers and theologians. Pope Clement IV summoned Aquinas to Rome to serve as a papal theologian. It was in Rome that Aquinas began writing his Summa Theologica,which was designed to serve as an introduction to theology students. It was certainly that and more.

Throughout the Summa, Aquinas refers to the teachings of many renowned philosophers and theologians, including Plato, Aristotle, Augustine, St. Ambrose and Boethius. He gives his greatest compliment to Aristotle, by referring to him as the Philosopher, as if there were no other worthy of that title. Similarly, Aquinas refers to Augustine as the Theologian. Aquinas’ discussion of natural law is clearly derived from Aristotle’s exposition on natural law as set forth in his Nicomachean Ethics.

Each of Aristotle’s main themes, happiness (eudaimonia), the good, the intellectual and moral virtues, are discussed and expanded on in the Summa. It has been suggested that the Summa constitutes a reconciliation between the ethical teachings of Aristotle and those of the Catholic Church. In many parts the Summa reads as if it were a commentary and application of Aristotle’s main themes from his Nicomachean Ethics, such as Aquinas’ discussion of natural law in Article 94. In a footnote, Mr. Kreeft reports that the best book ever written about Thomas Aquinas was Thomas Aquinas, the Dumb Ox, by G.K. Chesterton. In that book Chesterton describes the Summa as constituting “the baptism of Aristotle.”  In Article 94 Aquinas describes how natural law is the same for all men and the same everywhere, just as Aristotle describes it in Book V of his Ethics. In Article 95 Aquinas discusses human law, which he finds is based on God’s eternal law. 

In Books VII and X of the Ethics Aristotle asks the question of whether pleasure is the ultimate good to be sought. The majority of men, he notes, link happiness to pleasure, as would a sybarite. Aristotle concludes that since pleasure is a good that becomes more desirable when combined with another good, practical wisdom, for example, pleasure must not be the ultimate good to be sought. Likewise, in the Sixth Article of Question 2, of his section on ethics, Aquinas concludes that man’s happiness does not consist in pleasure, following similar reasoning to that of Aristotle.

Aristotle discusses in Book I of the Ethics whether honor is the ultimate good or end to be sought. Unfortunately, that benefit relies on those who would recognize one’s honor. Honor by its definition then is arbitrary, depending on the judgment or discernment of a third party. Accordingly, for Aristotle, honor is clearly not the ultimate good or end to be sought, because honor seems to depend on those who confer it rather than on him who receives it. Aquinas agrees, pointing out in his discussion of ethics that one should not perform virtuous works in order to be honored because honor is its own reward. Further, Aquinas notes, if one does perform virtuous works in pursuit of honors, then to that extent one would be surrendering to the vice of ambition.

For Aristotle, as explained in his Nichomachean Ethics, the end of man’s existence is happiness.  Happiness, for Aristotle, can be described as living well, acting well, living life in accord with virtue.  The goal of these virtues is to allow one to be able to live a life of happiness. Aristotle regards happiness, or eudaimonia, as the supreme practical good.  Aristotle’s vision of happiness can be achieved through an active life governed by reason and in accord with virtue.  All human actions and choices aim at some good.  Good has as many different meanings as the word “is.”  There are things good in themselves and things good as a means to the good.  The ultimate “good” may be defined as that for which everything else is done.  If there are several final ends, the one which is the most final is the one we are seeking.  Happiness is the most desirable of all the good things, the end at which all actions aim. The happy man will remain so throughout his life because he will be most often employed in doing and contemplating the things that will be in conformity with virtue.

Aquinas addresses the concept of happiness in the Summa in his Treatise on the Last End. His discussion focuses on man’s quest for happiness, which is exactly what Aristotle declares man’s last end to be in the Ethics. Like Aristotle, he discusses and discards the notion that man’s happiness could consist completely of pleasure, wealth or honor.  For Aquinas, the goal of human existence would be a union and eternal fellowship with God, which can only occur after one dies, as a gift from God to those who in life experienced salvation and redemption through Christ. Aquinas builds upon and expands Aristotle’s view of happiness. For Aquinas, man’s ultimate end or happiness can be found in the beatific vision of God.

Aquinas’ discussion of law in Questions 90 – 97 is fascinating and particularly relevant for the modern reader. He distinguishes God’s law, eternal law, from human law. In human law, he discusses natural law and positive law. He describes positive law as that which follows from man’s nature and is to a certain extent derived from God’s eternal law. For example, he would maintain that it would be a violation of natural law if a positive law allowed the unauthorized killing of another. It’s wrong to kill and a violation of God’s Commandment whether or not the law says “Thou shalt not kill.” The earliest reference to natural law in literature can be found iin Sophocles’ play Antigone, where Antigone says,  “For me it was not Zeus who made that order.  Nor did that justice who lives with the gods below mark out such laws to hold among mankind.  Nor did I think your orders were so strong that you, a mortal man, could over-run the gods’ unwritten and unfailing laws.  Not now, nor yesterday’s they always live, and no one knows their origin in time.  So not through fear of any man’s proud spirit would I be likely to neglect these laws.” 

Socrates and Plato pursued the idea of natural law. Plato supported the idea of natural law in the Republic. Aristotle built on that concept. He expands on the idea of natural law and natural justice in Book V of the Ethics. For Aristotle natural justice involves a sense of what is due or fair. Successors to Aristotle and Aquinas in this line of thought include John Locke, Blackstone and the Founding Fathers. Indeed, the Declaration of Independence reflects Aquinas’ view of natural law: “We hold these truths to be self-evident, that all men are created equal, that they are endowed by their Creator with certain unalienable Rights, that among these are Life, Liberty and the pursuit of Happiness.”

In modern times, Aquinas’ teaching on natural law continues to resonate. This can be demonstrated by reviewing a few sentences from Dr. Martin Luther King, Jr.’s, famous letter from the Birmingham Jail:

     “There are just laws and there are unjust laws.  I would be the first to advocate obeying just laws.  One has not only a legal but moral responsibility to obey just laws.       Conversely, one has a moral responsibility to disobey unjust laws.  I would agree with St. Augustine that ‘an unjust law is no law at all. ’Now, what is the difference       between the two?  How does one determine when a law is just or unjust?  A just law is a man-made code that squares with the moral law or the law of God.        An unjust law is a code that is out of harmony with the moral law.  To put it in the terms of Aquinas, an unjust law is a human law that is not rooted in eternal law and natural law.  Any law that uplifts human personality is just.  Any law that degrades human personality is unjust.  All segregation statutes are unjust because segregation distorts the soul and damages the personality.”

Peter Kreeft asserts that G.K. Chesterton’s book is the best biography of Thomas Aquinas. That may well be true. Certainly, Peter Kreeft’s Summa of the Summa should be regarded as one of the best commentaries on Thomas Aquinas’ Summa Theologica.

Daniel Gillespie is a Member of Our Lady of Mount Carmel Parish, Chicago, Illinois

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