instance is within the reach of human genius. Now, in conclusion, the
method which teaches adherence to the true order, and an exact enumeration
of all the conditions of the thing .sought includes all that gives
certitude to the rules of arithmetic.

But the chief ground of my satisfaction with thus method, was the
assurance I had of thereby exercising my reason in all matters, if not
with absolute perfection, at least with the greatest attainable by me:
besides, I was conscious that by its use my mind was becoming gradually
habituated to clearer and more distinct conceptions of its objects; and I
hoped also, from not having restricted this method to any particular
matter, to apply it to the difficulties of the other sciences, with not
less success than to those of algebra. I should not, however, on this
account have ventured at once on the examination of all the difficulties
of the sciences which presented themselves to me, for this would have been
contrary to the order prescribed in the method, but observing that the
knowledge of such is dependent on principles borrowed from philosophy, in
which I found nothing certain, I thought it necessary first of all to
endeavor to establish its principles. .And because I observed, besides,
that an inquiry of this kind was of all others of the greatest moment, and
one in which precipitancy and anticipation in judgment were most to be
dreaded, I thought that I ought not to approach it till I had reached a
more mature age (being at that time but twenty-three), and had first of
all employed much of my time in preparation for the work, as well by
eradicating from my mind all the erroneous opinions I had up to that
moment accepted, as by amassing variety of experience to afford materials
for my reasonings, and by continually exercising myself in my chosen
method with a view to increased skill in its application.