これらの格率をこのように確かめ，これらを，わたしの信念のなかでつねに第一であった信仰の真理とあわせて，ひとまず別にしたのちは，自分の意見の残り全部について，それらを自由に捨て去ることができると判断した。そしてこの企てを達成するためには，今までのことすべてを考えた炉部屋にそれ以上とどまるより，人びとと交わるほうがよいと思ったので，冬がまだ終わらぬうちに，わたしは再び旅に出た。こうしてその後まる九年の間，世界で演じられるあらゆる芝居のなかで，役者よりはむしろ観客になろうと努め，あちこちと巡り歩くばかりだった。そして各々のことがらで，疑わしい点，誤まりやすい点について，一つ一つ反省を加えながら，その間に，わたしの精神に前から忍びこんでいたあらゆる誤謬を根絶していった。しかし，だからといってわたしは，疑うためにだけ疑い，つねに非決定でいようとする懐疑論者たちを真似たわけではない。それどころか，わたしの計画は，自ら確信を得ること，緩い土や砂を取りのけて，岩や粘土を見つけだすことだけを目ざしていたからだ。これは相当にうまくいつたと思う。わたしが検討する命題の虚偽あるいは不確実性を根拠薄弱な憶測ではなく，明断で確かな推論によって明らかにしようと努めて，どんなに疑わしい命題にぶつかっても，そこからつねに，十分に確実な何らかの結論を引きだすことができたからである。たとえその命題が何も確実なものを含んでいないという，そのこと自体が結論にすぎなかった場合でも。そして古い住居を取り壊すときには，通常その取り壊した材料を新しい家の建築に利用するため取っておく。それと同じように，自分の意見のなかで，基礎が確かでないと判断したものをのこらず破壊していく場合にも，いろいろな観察をし，たくさんの実験を集積し，それらを，後になってもっと確実な意見を打ち立てるのに役立てた。そのうえ，わたしは自分に定めた方法を使いこなす練習をつづけていった。というのも，自分の思想すべてをこの方法の規則に従って導くよう全体にわたり努めたほかに，ときどき何時間かをさいて，とくに数学の難しい問題，さらには，数学の問題にほぼ似た形に直すことのできた他のいくつかの問題に，この方法を実際に適用した。それは，これら数学以外の問題を，わたしがあまり堅固でないと思っていた他の諸学問の原理すべてから切り離すことによっておこなった。この書物で説明されている多くの間題で，わたしが実行しているのを読者はごらんになるだろう。さてこうして，穏やかで邪念のない生活をするほか何の仕事もなく，快楽を悪徳から分けようと努め，また退屈せずに余暇をすごすために品位あるあらゆる気晴らしにふける人たちと，見かけは変わりのない生活をしながらも，わたしは自分の計画を追究しつづけ，ひたすら真理の認識に前進をつづけた。おそらく，ただ本を読んだり，学識者と付き合うだけだったよりも，はるかに先へ進んだのである。
Having thus provided myself with these maxims,
and having placed them in reserve along with
the truths of Faith, which have ever occupied
the first place in my belief, I came to the
conclusion that I might with freedom set
about ridding myself of what remained of
my opinions. And, inasmuch as I hoped to
be better able successfully to accomplish
this work by holding intercourse with mankind,
than by remaining longer shut up in the retirement
where these thoughts had occurred to me,
I betook me again to travelling before the
winter was well ended. And, during the nine
subsequent years, I did nothing but roam
from one place to another, desirous of being
a spectator rather than an actor in the plays
exhibited on the theatre of the world; and,
as I made it my business in each matter to
reflect particularly upon what might fairly
be doubted and prove a source of error, I
gradually rooted out from my mind all the
errors which had hitherto crept into it.
Not that in this I imitated the Sceptics
who doubt only that they may doubt, and seek
nothing beyond uncertainty itself; for, on
the contrary, my design was singly to find
ground of assurance, and cast aside the loose
earth and sand, that I might reach the rock
or the clay. In this, as appears to me, I
was successful enough; for, since I endeavoured
to discover the falsehood or incertitude
of the propositions I examined, not by feeble
conjectures, but by clear and certain reasonings,
I met with nothing so doubtful as not to
yield some conclusion of adequate certainty,
although this were merely the inference,
that the matter in question contained nothing
certain. And, just as in pulling down an
old house, we usually reserve the ruins to
contribute towards the erection, so, in destroying
such of my opinions as I judged to be ill-founded,
I made a variety of observations and acquired
an amount of experience of which I availed
myself in the establishment of more certain.
And further, I continued to exercise myself
in the Method I had prescribed; for, besides
taking care in general to conduct all my
thoughts according to its rules, I reserved
some hours from time to time which I expressly
devoted to the employment of the Method in
the solution of Mathematical difficulties,
or even in the solution likewise of some
questions belonging to other Sciences, but
which, by my having detached them from such
principles of these Sciences as were of inadequate
certainty, were rendered almost Mathematical:
the truth of this will be manifest from the
numerous examples contained in this volume.
1 And thus, without in appearance living
otherwise than those who, with no other occupation
than that of spending their lives agreeably
and innocently, study to sever pleasure from
vice, and who, that they may enjoy their
leisure without ennui, have recourse to such
pursuits as are honourable, I was nevertheless
prosecuting my design, and making greater
progress in the knowledge of truth, than
I might, perhaps, have made had I been engaged
in the perusal of books merely, or in holding
converse with men of letters.