be as inodorous as
possible; or as those who wish to impress figures on soft substances
do not allow any previous impression to remain, but begin by making the
surface as even and smooth as possible. In the same way that which is to
receive perpetually and through its whole extent the resemblances of all
eternal beings ought to be devoid of any particular form. Wherefore, the
mother and receptacle of all created and visible and in any way sensible
things, is not to be termed earth, or air, or fire, or water, or any of
their compounds or any of the elements from which these are derived, but
is an invisible and formless being which receives all things and in
some mysterious way partakes of the intelligible, and is most
incomprehensible. In saying this we shall not be far wrong; as far,
however, as we can attain to a knowledge of her from the previous
considerations, we may truly say that fire is that part of her nature
which from time to time is inflamed, and water that which is moistened,
and that the mother substance becomes earth and air, in so far as she
receives the impressions of them.

Let us consider this question more precisely. Is there any self-existent
fire? and do all those things which we call self-existent exist? or
are only those things which we see, or in some way perceive through the
bodily organs, truly existent, and nothing whatever besides them? And is
all that which we call an intelligible essence nothing at all, and
only a name? Here is a question which we must not leave unexamined or
undetermined, nor must we affirm too confidently that there can be no
decision; neither must we interpolate in our present long discourse
a digression equally long, but if it is possible to set forth a great
principle in a few words, that is just what we want.

Thus I state my view:--If mind and true opinion are two distinct
classes, then I say that there certainly are these self-existent ideas
unperceived by sense, and apprehended only by the mind; if, however, as
some say, true opinion differs in no respect from mind, then everything
that we perceive through the body is to be regarded as most real
and certain. But we must affirm them to be distinct, for they have a
distinct origin and are of a different nature; the one is implanted
in us by instruction, the other by persuasion; the one is always
accompanied by true reason, the other is without reason; the one cannot
be overcome by persuasion, but the other can: and