p1

^Ghayat Al-Hakim}&-
encounter them directly. Sensing is the feeling of those sensitive
forces towards the changes in how the senses react. For
instance, the medium of the force of seeing is the eye. This force
is derived from the fluid medium of the pupil of the eyes and so
are the rest of the senses. Sensing is the feeling of these forces
and achieving knowledge through them.
Proof is the philosophic criterion which leads to perfection
for whoever seeks a real objective. A branch of knowledge can
exist by examining the particular characteristics of that objective
as well as through examining its subjective fixed introductions.
There are two branches of knowledge: knowledge by belief and
knowledge by perception. Knowledge can be also be achieved
by accepted and convincing statements and in this case, proof is
termed as persuasive.
I first read about this proof in the works of Ptolemy and then
I discovered by practice the effect of this talisman which I have
already described in the First Book. Whenever I researched a
certain topic in books written by the wise, I always found what I
wanted and I was happy to discover the truth.
Going back to our objective, I would like to say that no one
can find out how the higher world affects the lower world
without having full knowledge of the different branches of
philosophy, I mean the mathematical, physical and metaphysical
arts. He who falls short in acquiring these sciences will
not be able to fulfill his real goal because the primary
perquisites of knowledge are taken from these three branches of
philosophy. As for the mathematical art, without numbers, the
movements of the higher bodies and the methods by which
geometry is obtained cannot be learned. Furthermore,
mathematical survey is a prerequisite for learning the geometry
of the celestial bodies; without it, star observation or their
measurements, which are primarily derived from the proofs of
mathematical survey, will be impossible to learn. Moreover, the
art of matching, by which similarity and difference can be
67