PETER KREEFT

A Summa of the Summa

The Essential Philosophical Passages of St. Thomas Aquinas’ Summa Theologica

Edited and Explained for Beginners

Passages from the Summa Theologica are taken from the translation done in 1920 by The Fathers of the English Dominican Province. Used with permission.

Cover art credit: SCALA/Art Resource, New York

Detail of St. Thomas Aquinas from a work entitled

Trionfa di S. Tommaso d’Aquino

by Andrea di Buonaiuto

in the Spanish chapel of

St. Maria Novella, Florence

Cover design by Roxanne Mei Lum

© 1990 Ignatius Press, San Francisco

With ecclesiastical approval

All rights reserved

ISBN 978-0-89870-300-9

Library of Congress catalogue number 90-81772

To W. Norris Clark, S.J.

More than a great Thomist;

A little Thomas

CONTENTS

Introduction

Glossary

I. Methodology: Theology as a Science (I, 1)

II. Proofs for the Existence of God (I, 2)

III. The Nature of God (I, 3–26)

IV. Cosmology: Creation and Providence (I, 44–49, 65, 103–5)

V. Anthropology: Body and Soul (I, 75–78)

VI. Epistemology and Psychology (I, 79–93)

VII. Ethics

A. Happiness (I-II, 1–5)

B. Willing (I-II, 6–13)

C. Good and Evil (I-II, 18–21)

D. Love (I-II, 26–29)

E. Virtues (I-II, 55–70)

F. Vices (I-II, 71–89)

G. Law (I-II, 90–108)

Index

INTRODUCTION

I couldn’t make any judgment on the Summa, except to say this: I read it every night before I go to bed. If my mother were to come in during the process and say, “Turn off that light. It’s late,” I with lifted finger and broad bland beatific expression, would reply, “On the contrary, I answer that the light, being eternal and limitless, cannot be turned off. Shut your eyes,” or some such thing. In any case I feel I can personally guarantee that St. Thomas loved God because for the life of me I cannot help loving St. Thomas.

—Flannery O’Connor, The Habit of Being

I. On St. Thomas

St. Thomas Aquinas is certainly one of the greatest philosophers who ever lived (to my mind he is the greatest), for at least eight reasons: truth, common sense, practicality, clarity, profundity, orthodoxy, medievalism, and modernity.

First, and most simply, he told the truth—that simple and unfashionable purpose of philosophy that is so often fudged (“nuanced”) or forgotten today. The following quotation should be chiseled on the doorposts of every philosophy department in the world: “The study of philosophy is not the study of what men have opined, but of what is the truth.”

2. Descartes says that the one thing he learned about philosophy in the university that stuck with him was that one could not imagine any doctrine so bizarre or unbelievable that it has not been seriously taught by some philosopher or other. What was true already in 1637 is triply true today. St. Thomas, however, is the master of common sense. He has an uncanny knack of sniffing out the obviously right position amid a hundred wrong ones. This holds true especially in ethics, the real test of a philosopher. Some great philosophers, ...