- Chapter I
What Light is, and in What manner it comes to us.
- Chapter II
The Property, which Light has of reflecting itself, was not truly known. It is not reflected by the solid Parts of Bodies as vulgarly believed.
- Chapter III
Of the property which Light has of refracting in passing from one Substance into another, and of taking a new Course in its Progression.
- Chapter IV
Of the Form of the Eye, and in what manner Light enters and acts in that Organ.
- Chapter V
Of Looking–Glasses, and Telescopes: Reasons given by Mathematicians for the Mysteries of Vision; that those Reasons are not altogether sufficient.
- Chapter VI
In what Manner we know Distances, Magnitudes, Figures, and Situations.
- Chapter VII
Of the Cause of the breaking of the Rays of Light in passing from one Medium to another; that this Cause is a general Law of Nature unknown before Newton; that the Inflection of Light is also an Effect of the same Cause.
- Voltaire discusses a case wherein Dr. William Cheselden healed the sight of a blind teenage boy. Voltaire notes that upon seeing for the first time, the boy thought the images were resting on his eyeballs.[3]
- Chapter VIII
The wonderful Effects of the Refraction of Light. The several Rays of Light have all possible Colours in themselves; what Refrangibility is. New Discoveries.
- Chapter IX
The Cause of Refrangibility; from which it appears that there are indivisible Bodies in Nature.
- Chapter X
Proof that there are indivisible Atoms, and that the simple Particles of Light are Atoms of that kind. Discoveries continued.
- Chapter XI
Of the Rainbow; that Phenomenon a necessary Effect of the Laws of Refrangibility.
- Chapter XII
New Discoveries touching the Cause of Colours, which confirm the preceding Doctrine; Demonstration that Colours are occasioned by the Density and Thickness of the Parts of which Bodies are composed (or the Thickness of the Parts that compose the Surfaces only).
- Chapter XIII
Consequences of these Discoveries. The mutual Action of Bodies upon Light.
- Chapter XIV
Of the Resemblance between the seven Primitive Colours and the seven Notes in Musick.
- Chapter XV
Introductory Ideas concerning Gravity and the Laws of Attraction: That the Opinion of a subtil Matter, Vortices, and a Plenitude, ought to be rejected (But not that subtile Aether which Sir Isaac makes the Cause of Attraction, Refraction, Animal Motion, &c. which pervades the Universe).
- Chapter XVI
That the Vortices and Plenitude of Descartes are impossible, and consequently that there is some other Cause of Gravity.
- Chapter XVII
What is meant by Vacuity and Space, without which there could be neither Gravity nor Motion.
- Chapter XVIII
Gravitation demonstrated from the Discoveries of Galileo and Newton: That the Moon revolves in her Orbit by the Force of this Gravitation.
- Chapter XIX
That Gravitation and Attraction direct all the Planets in their Courses.
- Chapter XX
Demonstrations of the Laws of Gravitation, drawn from the Rules of Kepler: That one of these Laws of Kepler demonstrates the Motion of the Earth.
- Chapter XXI
New Proofs of Attraction. That the Inequalities of the Motion and Orbit of the Moon are necessarily the Effects of Attraction.
- Chapter XXII
New Proofs and New Effects of Gravitation. That this Power is in every Particle of Matter. Discoveries dependent on this Principle.
- Chapter XXIII
The Theory of our Planetary World.
- Chapter XXIV
Of the Zodiacal Light, the Comets, and the fixed Stars.
- Chapter XXV
Of the second Inequalities of the Motion of the Satellites, and the Phaenomena that depend thereon.
- Glossary
Explanations of the hard Words used in this Treatise.