Note (return) — Chapter XIII

The only qualities of atoms are form, magnitude, and density. All the other sensible qualities of matter--the secondary qualities-- as color, odor, sweetness, bitterness, etc.--are necessarily inherent in form. All secondary qualities are changeable, but the primary atoms are unchangeable; "for in the dissolution of combined bodies there must be something solid and indestructible, of such a kind that it will not change, either into what does not exist, or out of what does not exist, but the change results from a simple displacement of parts, which is the most usual case, or from an addition or subtraction of particles." 794