— 643 —
The true method of advancing Knowledge, is by considering our abstract Ideas.
      §7. We must therefore, if we will proceed, as Reason advises,
adapt our methods of Enquiry to the nature of the Ideas we examine, and
the Truth we search after. General and certain Truths, are only
founded in the Habitudes and Relations of abstract Ideas. A sagacious
and methodical application of our Thoughts, for the finding out
these Relations, is the only way to discover all, that can be put,
with Truth and Certainty concerning them, into general Proposi-
tions. By what steps we are to proceed in these, is to be learned in
the Schools of the Mathematicians, who from very plain and easy
beginnings, by gentle degrees, and a continued Chain of Reasonings,
proceed to the discovery and demonstration of Truths, that appear
at first sight beyond humane Capacity. The Art of finding Proofs,
and the admirable Methods they have invented for the singling out,
and laying in order those intermediate Ideas, that demonstratively
shew the equality or inequality of unapplicable quantities, is that
which has carried them so far, and produced such wonderful and
unexpected discoveries: but whether something like this, in respect
of other Ideas, as well as those of magnitude, may not in time be
found out, I will not determine. This, I think, I may say, that if
other Ideas, that are the real, as well as nominal Essences of their
Species, were pursued in the way familiar to Mathematicians, they
would carry our Thoughts farther, and with greater evidence and
clearness, than possibly we are apt to imagine.
Locke Hum IV, 12, §7, p. 643