which we have so far sensitive knowledge: but
the causes, manner, and certainty of their production, for the two
foregoing reasons, we must be content to be very ignorant of. In these
we can go no further than particular experience informs us of matter of
fact, and by analogy to guess what effects the like bodies are, upon
other trials, like to produce. But as to a PERFECT SCIENCE of natural
bodies, (not to mention spiritual beings,) we are, I think, so far from
being capable of any such thing, that I conclude it lost labour to seek
after it.

30. Thirdly A third cause, Want of Tracing our ideas.

THIRDLY, Where we have adequate ideas, and where there is a certain and
discoverable connexion between them, yet we are often ignorant, for
want of tracing those ideas which we have or may have; and for want of
finding out those intermediate ideas, which may show us what habitude of
agreement or disagreement they have one with another. And thus many are
ignorant of mathematical truths, not out of any imperfection of their
faculties, or uncertainty in the things themselves, but for want of
application in acquiring, examining, and by due ways comparing those
ideas. That which has most contributed to hinder the due tracing of our
ideas, and finding out their relations, and agreements or disagreements,
one with another, has been, I suppose, the ill use of words. It is
impossible that men should ever truly seek or certainly discover the
agreement or disagreement of ideas themselves, whilst their thoughts
flutter about, or stick only in sounds of doubtful and uncertain
significations. Mathematicians abstracting their thoughts from names,
and accustoming themselves to set before their minds the ideas
themselves that they would consider, and not sounds instead of them,
have avoided thereby a great part of that perplexity, puddering, and
confusion, which has so much hindered men's progress in other parts of
knowledge. For whilst they stick in words of undetermined and uncertain
signification, they are unable to distinguish true from false, certain
from probable, consistent from inconsistent, in their own opinions. This
having been the fate or misfortune of a great part of men of letters,
the increase brought into the stock of real knowledge has been very
little, in proportion to the schools disputes, and writings, the world
has been filled with; whilst students, being lost in the great wood of
words, knew not whereabouts they were,