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which is born and ends {144} in the mind is termed scientific; that
which issues from science and ends in manual work is termed
semi-mechanical. But I consider vain and full of error that science
which is not the offspring of experience, mother of all certitude, and
which does not result in established experience, that is to say, whose
origin, middle and end do not pass through any of the five senses. And
if we doubt of everything we perceive by the senses, should we not
doubt much more of what is contrary to the senses, such as the
existence of God and of the soul, and similar matters constantly under
dispute and contention?

And it is truly the case that where reason is lacking it is
supplemented by noise, which never happens in matters of certainty. On
account of this we will say that where there is noise there is no true
science, because truth has one end only, which, when it is made known,
eternally silences controversy, and should controversy come to life
again, it is lying and confused knowledge which is reborn, and not
certainty. But true science is that which has penetrated into the
senses through experience and silenced the tongue of the disputers, and
which does not feed those who investigate it with dreams, but proceeds
from the basis of primary truths and established principles
successively and by true sequence to the end; as, for instance, what
comes under the heading of elementary mathematics, {145} that is,
numeration and measurement, termed arithmetic and geometry, which treat
with the highest truth of the discontinued and continued quantity.
Here there will be no dispute as to whether twice three make more or
less than six, nor whether two angles of a triangle are less than two
right angles, but eternal silence shall ignore all controversy, and the
devotees of the true science will finish their studies in peace, which
the lying mental sciences cannot do. And if thou sayest that true and
established science of this kind is a species of mechanics, because
they can only be completed by the hand, I will say the same of all the
arts, such as that which passes through the hand of the sculptor, which
is a kind of drawing, a part of painting; and astrology and the other
sciences pass through manual operation, but they are mental in the
first place, as painting, which first of all exists in the mind of the
composer, and cannot attain to fulfilment without manual labour. With
regard to painting, its t