were attentively considered, are the most evident and clear which
the human mind can know. Thus by considering that he who strives to
doubt of all is unable nevertheless to doubt that he is while he
doubts, and that what reasons thus, in not being able to doubt of
itself and doubting nevertheless of everything else, is not that
which we call our body, but what we name our mind or thought, I have
taken the existence of this thought for the first principle, from
which I very clearly deduced the following truths, namely, that
there is a God who is the author of all that is in the world, and
who, being the source of all truth, cannot have created our
understanding of such a nature as to be deceived in the judgments it
forms of the things of which it possesses a very clear and distinct
perception. Those are all the principles of which I avail myself
touching immaterial or metaphysical objects, from which I most
clearly deduce these other principles of physical or corporeal
things, namely, that there are bodies extended in length, breadth,
and depth, which are of diverse figures and are moved in a variety
of ways. Such are in sum the principles from which I deduce all
other truths. The second circumstance that proves the clearness of
these principles is, that they have been known in all ages, and even
received as true and indubitable by all men, with the exception only
of the existence of God, which has been doubted by some, because
they attributed too much to the perceptions of the senses, and God
can neither be seen nor touched.

But, though all the truths which I class among my principles were
known at all times, and by all men, nevertheless, there has been no
one up to the present, who, so far as I know, has adopted them as
principles of philosophy: in other words, as such that we can deduce
from them the knowledge of whatever else is in the world. It