summa-contra-gentiles

its
CHAPTER XCVIII 295
proper specific nature, but only as regards the common
nature of their genus.
Accordingly some^ say that one separate substance is the
efficient cause of another. Now in every efficient cause
there must be the image of its effect, and likewise in every
effect there must be the likeness of its cause : because every
agent produces its like. Hence in the higher separate
substance there exists the likeness of the lower, as in the
cause there is the likeness of its effect; while in the lower
there is the likeness of the higher, as in the efifect there is
the likeness of its cause. Now if we consider non-univocal
causes, the likeness of the effect exists in the cause in a more
eminent manner, and the likeness of the cause is in its effect
in a less eminent manner. And the higher separate substances
must needs be causes of this kind with respect to
the lower separate substances : because they are placed in
various degrees which are not of one species. Therefore a
lower separate substance knows a higher according to the
mode of the substance knowing, and not according to the
mode of the substance known, but in a lower manner :
whereas the higher knows the lower in a more eminent way.
This is the meaning of the statement in De Causis,^ that an
intelligence kno'v:s ivhat is below it, and what is above it,
according to the mode of its substance : because the one is
the cause of the other.
But since we have shown above^ that intellectual separate
substances are not composed of matter and form, they
cannot be caused except by way of creation. Now to
create belongs to God alone, as we proved above.* Therefore
one separate substance cannot be the cause of another.
Further. It has been proved^ that the principal parts of
the universe are all created immediately by God. Therefore
one of them is not caused by another. Now each of the
separate substances is a principal part of the universe, much
more than the sun or moon : since each of them has its
proper species, which is
also more noble than any species
* Avicenna, Meiaph., tract ix. 4.
* § vii.
« Chs. l.,Ii. * Ch. ni. » Ch. xlii.