summa-contra-gentiles

CHAPTER LXXXIX 267
change, not of form, but of quantity. As to the sensitive
and intellective part, it is clear that it has no operation
appropriate to such a formation. It remains then that the
formation of the body, especially as regards the foremost
and principal parts, is not from the form of the subject
generated, nor from a formative power acting by virtue of
that form, but from (a formative power) acting by virtue of
the generative soul of the father, the work of which soul is
to produce the specific like of the generator.
Accordingly this formative power remains the same in
the aforesaid spirit from the beginning of the formation
until the end. Yet the species of the subject formed remains
not the same : because at first it has the form of semen,
afterwards of blood, and so onwards until it arrives at its
final complement. For although the generation of simple
bodies does not proceed in order, since each of them has an
immediate form of primary matter; in the generation of
other bodies, there must be an order in the generations, by
intermediate forms between the first
reason of the many
elemental form and the final form which is the term of
generation ; wherefore there are a number of generations
and corruptions following one another.
Nor is it unreasonable if one of the intermediates be
generated and then at once interrupted, because the intermediate
stages have not a complete species but are on the
way to a species hence : they are generated, not that they
may remain, but that the final term of generation may be
reached through them. Nor need we wonder if the transmutation
of generation be not throughout continuous, and
that there are many intermediate generations ; for this
happens also in alteration and growth, since neither alteration
nor growth is continuous throughout, but only local
movement is truly continuous, as we find proved in
8 Physic ."^
Accordingly, the more noble a form is and the further
removed it is from the elemental form, the more numerous
must needs be the intermediate forms, through which the
* vii. 8 seqq.