Commentaria in octo libros Physicorum
COMMENTARY ON ARISTOTLE'S PHYSICS

by
Thomas Aquinas

Books I-II translated by
Richard J. Blackwell, Richard J. Spath & W. Edmund Thirlkel
Yale U.P., 1963

Books III-VIII translated by
Pierre H. Conway, O.P.
Colege of St. Mary of the Springs, Columbus, Ohio
1958-1962

html edition by Joseph Kenny, O.P.
For my own summary of Books I-VII, see Nature
TABLE OF CONTENTS

    BOOK I: THE PRINCIPLES OF NATURAL THINGS
  1. The matter and the subject of natural science
  2. The opinions of the ancient philosophers about the principles of nature and of beings
  3. The assertion of Parmenides and Melissus that all things are one being
  4. Later philosophers' same error: that the one and the many could not in any way concur
  5. The argument of Melissus is answered
  6. The argument of Parmenides is answered
  7. He disproves the position of those who said that non-being is something
  8. Opinions of physicists who spoke of the principles as natural philosophers
  9. The opinion of Anaxagoras that the principles are infinite
  10. Opinions of the ancients concerning the contrariety of the first principles
  11. There are three principles of natural things, no more, no less
  12. In every coming-to-be three principles are to be found: subject, terminus of production, its opposite
  13. There are two per se principles (matter & form) and one per accidens principle (privation)
  14. Problems and errors of the ancients springing from ignorance of matter are resolved
  15. Matter is distinguished from privation; it is neither generable nor corruptible per se
    BOOK II: THE PRINCIPLES OF NATURAL SCIENCE
  1. What is nature? What things have a nature? What things are 'according to nature'?
  2. Nature is both matter and form, but primarily form
  3. How physics and mathematics differ in their consideration of the same thing
  4. Physics considers not only matter but also every form existing in matter
  5. Physics determines what the causes are and how many species of causes there are
  6. The different modes of causing, and what is consequent upon these modes
  7. Opinions about fortune and chance
  8. Distinctions among effects and causes; a definition of fortune
  9. What ancient philosophers and the common man say about fortune
  10. The difference between chance and fortune; the causes are four, no more, no less
  11. Natural philosophy demonstrates from all four causes
  12. Those who deny that nature acts for an end
  13. That nature acts for an end
  14. That this is so from evidence by which some conclude to the opposite position
  15. How necessity is found in natural things
    BOOK III: MOBILE BEING IN COMMON
  1. Need for defining motion and things relating to it
  2. Definition of motion
  3. Justification of the definition of motion
  4. Action and passion are the same motion
  5. Motion as from the agent and in the patient
  6. Early opinions of the infinite
  7. Arguments for and against the infinite
  8. No sensible infinite
  9. No infinite body shown absolutely
  10. The infinite as existing in potency
  11. Definition of the infinite
  12. Explanations in the light of the definition of the infinite
  13. Solution of arguments in favor of existence of the infinite

    BOOK IV: PLACE, VOID AND TIME

  1. Place, its existence
  2. Six dialectical reasons showing place does not exist
  3. Is place matter or form?
  4. Prerequisites to determining the truth about place
  5. Necessary previous notions for the definition of place
  6. The definition of place
  7. The definition of place (n. 472)
  8. The definition of place is used to solve the original problems; the properties of place are justified
  9. The void— reasons for and against
  10. The meaning of “void”—refutation of those positing the void
  11. From motion there is known to be no separated void
  12. From the fastness and slowness of motion, a separated void is disproved
  13. Non-existence of the void from the void itself
  14. There is no void within bodies
  15. Does time exist., and is there the same “now” in the whole of time?
  16. Dialectical inquiring into what time is, and how it is related to motion
  17. The definition of time, given and explained
  18. How the same “now” is or is not in a whole time
  19. From the definition of time certain things are
  20. How things are, and are not, in time
  21. The meaning or “now” and related terms
  22. How corruption is attributed to time; All motion and changes are in time
  23. The Problems are solved as to the existence of unity of time

    BOOK V: DIVISION OF MOTION INTO ITS SPECIES

  1. Per se notion is distinguished from per accidens
  2. The species of change; which one is motion
  3. Per se motion is not in other predicaments than quantity, quality, and place
  4. Motion is solely in quantity, quality, and place
  5. The definitions of “in contact,” “consecutive,” “continuous”
  6. Generic, specific, and numerical unity of motion
  7. Numerical unity of motion (continued)
  8. Contrariety of motions
  9. Contrariety of rest to motion, and of rest to rest
  10. Certain difficulties are resolved

    BOOK VI: DIVISION OF MOTION INTO QUANTITATIVE PARTS

  1. No continuum is composed of indivisibles
  2. Motion composed of indivisibles follows a continuum composed of indivisibles—impossibility of the former
  3. Time follows magnitude in divisibility and conversely
  4. Proof that no continuum is indivisible
  5. The “now” as the indivisible of time. Everything that moves is divisible. Difficulties solved
  6. Two manners of dividing motion. What things are co-divided with motion
  7. The time in which something is first changed is indivisible. How a first may, and may not, be taken in motion
  8. Before every “being moved” is a “having been moved,” and conversely
  9. Finite and infinite are found simultaneously in magnitude, time, mobile, and motion
  10. Things pertaining to the division of “coming to a stand” and “rest”
  11. Zeno's arguments excluding all motion are resolved
  12. What is indivisible according to quantity is moved only per accidens
  13. By nature, no change is infinite. How motion may be infinite in time

    BOOK VII: EXISTENCE OF THE FIRST MOTION AND FIRST MOVER

  1. It is necessary that whatever is moved, be moved by another
  2. No process to infinity in movers and moved. One must arrive at a first mover unmoved
  3. In local motion, mover and moved must be together
  4. It is shown in alteration, and growth and decrease, that mover and moved are together
  5. Alteration is not found in the first species of quality (form and figure), nor in the first (habit and disposition)
  6. No alteration in the first species of quality as to habits of the soul
  7. The comparing of motions: what is required
  8. Which motions may be compared
  9. Rules for the comparison of motions

    BOOK VIII: NATURE OF THE FIRST MOTION AND FIRST MOVER

  1. Opinions on the beginning and end of motion
  2. Arguments for the eternity of motion
  3. Arguments against Anaxagoras and Empedocles
  4. Solution of arguments concluding motion was not always
  5. Five ways in which things may be disposed with respect to motion or rest. Two first excluded
  6. A third member of the division is rejected
  7. Universally, whatever is moved, is moved by another
  8. What moves the heavy and the light. Everything moved, moved by another
  9. No process to infinity in movers. Not every mover need be moved
  10. In that which moves itself, one part moves and the other is moved
  11. How the parts of something moving itself are related
  12. The first mover is not moved, but is one and perpetual
  13. The first mover is perpetual and wholly unmoved, as shown from moving principles
  14. Many reasons why local motion is the first motion
  15. Local motion alone can be continuous and perpetual
  16. No change of place can be continuous and perpetual, except the circular
  17. Certain doubts
  18. Dialectical reasons to show reflex motion is not continuous
  19. Proper reasons why circular motion can be continuous, and why it is the first so
  20. Dialectical reasons why circular motion is continuous and first. Confirmation from the ancients
  21. Limitations of a finite mover
  22. Diversity of movers annuls continuity of motion
  23. The first mover can have no magnitude