— 526 —
Thirdly, of Co-existence.
      §6. Thirdly, The third sort of Agreement, or Disagreement to be
found in our Ideas, which the Perception of the Mind is employ’d
— 527 —
about, is Co-existence, or Non-co-existence in the same Subject; and this
belongs particularly to Substances. Thus when we pronounce
concerning Gold, that it is fixed, our Knowledge of this Truth
amounts to no more but this, that fixedness, or a power to remain
in the Fire unconsumed, is an Idea, that always accompanies, and is
join’d with that particular sort of Yellowness, Weight, Fusibility,
Malleableness, and Solubility in Aqua Regia, which make our
complex Idea, signified by the word Gold.
Locke Hum IV, 1, §6, pp. 526-527