— 139 —
      §19. Let us consider the red and white colours in Porphyre: Hin-
der light but from striking on it, and its Colours Vanish; it no
longer produces any such Ideas in us: Upon the return of Light, it
produces these appearances on us again. Can any one think any real
alterations are made in the Porphyre, by the presence or absence of
Light; and that those Ideas of whiteness and redness, are really in
Porphyre in the light, when ’tis plain it has no colour in the dark? It has,
indeed, such a Configuration of Particles, both Night and Day, as
are apt by the Rays of Light rebounding from some parts of that
hard Stone, to produce in us the Idea of redness, and from others the
Idea of whiteness: But whiteness or redness are not in it at any time,
but such a texture, that hath the power to produce such a sensation
in us.
Locke Hum II, 8, §19, p. 139