CONTENTS

BOOK I

1. The scope and method of this book.
2. The problem: the number and character of the first principles of nature.
185ª 20. Reality is not one in the way that Parmenides and Melissus supposed.
3. Refutation of their arguments.
4. Statement and examination of the opinions of the natural philosophers.
5. The principles are contraries.
6. The principles are two, or three, in number.
7. The number and nature of the principles.
8. The true opinion removes the difficulty felt by the early philosophers.
9. Further reflections on the first principles of nature.

BOOK II

1. Nature and the natural.

2. Distinction of the natural philosopher from the mathematician and the metaphysician.

3. The essential conditions.
4. The opinions of others about chance and spontaneity.
5. Do chance and spontaneity exist? What is chance and what are its characteristics?
6. Distinction between chance and spontaneity, and between both and the essential conditions of change.

7. The physicist demonstrates by means of the four conditions of change.
8. Does nature act for an end?
9. The sense in which necessity is present in natural things.