22. An excursion into natural philosophy.
I have in what just goes before been engaged in physical inquiries a
little further than perhaps I intended. But, it being necessary to make the nature of sensation a little understood;
and to make the difference between the qualities in bodies, and the ideas produced by them in the mind, to be
distinctly conceived, without which it were impossible to discourse intelligibly of them;--I hope I shall be
pardoned this little excursion into natural philosophy; it being necessary in our present inquiry to distinguish the
primary and real qualities of bodies, which are always in them (viz., solidity, extension, figure, number, and
motion, or rest, and are sometimes perceived by us, viz., when the bodies they are in are big enough singly to be
discerned), from those secondary and imputed qualities, which are but the powers of several combinations of
those primary ones, when they operate without being distinctly discerned;--whereby we may also come to know
what ideas are, and what are not, resemblances of something really existing in the bodies we denominate from
them.
