Sentiments concerning nature with which philosophers were delighted
Book I.
Book II.
Book III.
Book IV.
Book V
These rods and the mock-suns are constituted of a double nature, a real subsistence, and a mere appearance; - of a real subsistence, because the clouds are the object of our eyes; of a mere appearance, for their proper color is not seen, but that which is adventitious. The like affections, natural and adventitious, in all such things do happen.