The subject that perceives a sense-object must itself be single, and
grasp this object in its totality, by one and the same power. This
happens when by several organs we perceive several qualities of a
single object, or when, by a single organ, we embrace a single complex
object in its totality, as, for instance, a face. It is not one
principle that sees the face, and another one that sees the eyes; it
is the "same principle" which embraces everything at once. Doubtless
we do receive a sense-impression by the eyes, and another by the ears;
but both of them must end in some single principle. How, indeed, could
any decision be reached about the difference of sense-impressions
unless they all converged toward the same principle? The latter is
like a centre, and the individual sensations are like radii which
from the circumference radiate towards the centre of a circle. This
central principle is essentially single. If it was divisible, and if
sense-impressions were directed towards two points at a distance from
each other, such as the extremities of the same line, they would either
still converge towards one and the same point, as, for instance, the
middle (of the line), or one part would feel one thing, and another
something else. It would be absolutely as if I felt one thing, and you
felt another, when placed in the presence of one and the same thing (as
thought Aristotle, de Anima[53]). Facts, therefore, demonstrate that
sensations centre in one and the same principle; as visible images are
centred in the pupil of the eye; otherwise how could we, through the
pupil, see the greatest objects? So much the more, therefore, must
the sensations that centre in the (Stoic) "directing principle"[54]
resemble indivisible intuitions and be perceived by an indivisible
principle. If the latter possessed extension, it could, like the
sense-object, be divided; each of its parts would thus perceive one
of the parts of the sense-object, and nothing within us would grasp
the object in its totality. The subject that perceives must then be
entirely one; otherwise, how could it be divided? In that case it could
not be made to coincide with the sense-object, as two equal figures
superimposed on each other, because the directing principle does not
have an extension equal to that of the sense-object. How then will we
carry out the division? Must the subject that feels contain as many
parts as there are in the sense-object? Will each part of the soul, in
its turn, feel by its own parts, or will (we decide that) the parts of
parts will not feel? Neither is that likely. If, on the other hand,
each part feels the entire object, and if each magnitude is divisible
to infinity, the result is that, for a single object, there will be an
infinity of sensations in each part of the soul; and, so much the more,
an infinity of images in the principle that directs us. (This, however,
is the opposite of the actual state of affairs.)