The doubt of Descartes is not the expression of a resigned spirit which
renounces the unattainable; it is precept, not doctrine, the starting point
of philosophy, not its conclusion, a methodological instrument in the hand
of a strong and confident longing for truth, which makes use of doubt to
find the indubitable. It is not aimed at the possibility of attaining
knowledge, but at the opinion that it has already been attained, at the
credulity of the age, at its excessive tendency toward historical and
poly-historical study, which confuses the acquisition and handing down of
information with knowledge of the truth. That knowledge alone is certain
which is self-attained and self-tested--and this cannot be learned
or handed down; it can only be rediscovered through examination and
experience. Instead of taking one's own unsupported conjectures or the
opinions of others as a guide, the secret of the search for truth is to
become independent and of age, to think for one's self; and the only remedy
against the dangers of self-deception and the ease of repetition is to be
found in doubting everything hitherto considered true. This is the meaning
of the Cartesian doubt, which is more comprehensive and more thorough
than the Baconian. Descartes disputed only the certitude of the knowledge
previously attained, not the possibility of knowledge--for of the latter no
man is more firmly convinced than he. He is a rationalist, not a skeptic.
The intellect is assured against error just as soon as, freed from
hindrances, it remains true to itself, as it puts forth all its powers and
lets nothing pass for truth which is not clearly and distinctly known.
Descartes demands the same thing for the human understanding as Rousseau at
a later period for the heart: a return to uncorrupted nature. This faith in
the unartificial, the original, the natural, this radical and naturalistic
tendency is characteristically French. The purification of the mind, its
deliverance from the rubbish of scholastic learning, from the pressure of
authority, and from inert acceptance of the thinking of others--this is
all. Descartes finds the clearest proof of the mind's capacity for truth in