This is why the
female does not produce offspring by herself, for she needs a
principle, i.e. something to begin the movement in the embryo and to
define the form it is to assume. Yet in some animals, as birds, the
nature of the female unassisted can generate to a certain extent,
for they do form something, only it is incomplete; I mean the
so-called wind-eggs.
22
For the same reason the development of the embryo takes place in the
female; neither the male himself nor the female emits semen into the
male, but the female receives within herself the share contributed
by both, because in the female is the material from which is made
the resulting product. Not only must the mass of material exist
there from which the embryo is formed in the first instance, but
further material must constantly be added that it may increase in
size. Therefore the birth must take place in the female. For the
carpenter must keep in close connexion with his timber and the
potter with his clay, and generally all workmanship and the ultimate
movement imparted to matter must be connected with the material
concerned, as, for instance, architecture is in the buildings it
makes.
From these considerations we may also gather how it is that the male
contributes to generation. The male does not emit semen at all in some
animals, and where he does this is no part of the resulting embryo;
just so no material part comes from the carpenter to the material,
i.
Pages:
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63