can
come to know? Much less have we distinct ideas of their different
natures, conditions, states, powers, and several constitutions wherein
they agree or differ from one another and from us. And, therefore, in
what concerns their different species and properties we are in absolute
ignorance.

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 connection 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,
&c. 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 appearin