28. Secondly, Another cause, want of a discoverable connexion between ideas we have.
Secondly, What a small part of the
substantial beings that are in the universe the want of ideas leaves open to our knowledge, we have seen. In the
next place, another cause of ignorance, of no less moment, is a want of a discoverable connexion between those
ideas we have. For wherever we want that, we are utterly incapable of universal and certain knowledge; and are,
in the former case, left only to observation and experiment: which, how narrow and confined it is, how far from
general knowledge we need not be told. I shall give some few instances of this cause of our ignorance, and so
leave it. It is evident that the bulk, figure, and motion of several bodies about us produce in us several sensations,
as of colours, sounds, tastes, smells, pleasure, and pain, etc. These mechanical affections of bodies having no
affinity at all with those ideas they produce in us, (there being no conceivable connexion between any impulse of
any sort of body and any perception of a colour or smell which we find in our minds,) we can have no distinct
knowledge of such operations beyond our experience; and can reason no otherwise about them, than as effects
produced by the appointment of an infinitely Wise Agent, which perfectly surpass our comprehensions. As the
ideas of sensible secondary qualities which we have in our minds, can by us be no way deduced from bodily
causes, nor any correspondence or connexion be found between them and those primary qualities which
(experience shows us) produce them in us; so, on the other side, the operation of our minds upon our bodies is as
inconceivable. How any thought should produce a motion in body is as remote from the nature of our ideas, as
how any body should produce any thought in the mind. That it is so, if experience did not convince us, the
consideration of the things themselves would never be able in the least to discover to us. These, and the like,
though they have a constant and regular connexion in the ordinary course of things; yet that connexion being not
discoverable in the ideas themselves, which appearing to have no necessary dependence one on another, we can
attribute their connexion to nothing else but the arbitrary determination of that All-wise Agent who has made
them to be, and to operate as they do, in a way wholly above our weak understandings to conceive.
