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On The Generation Of Animals   

similarity and analogy. For there is a slight distinction of this
sort, since even in plants we find in the same kind some trees which
bear fruit and others which, while bearing none themselves, yet
contribute to the ripening of the fruits of those which do, as in
the case of the fig-tree and caprifig.

The same holds good also in plants, some coming into being from seed
and others, as it were, by the spontaneous action of Nature, arising
either from decomposition of the earth or of some parts in other
plants, for some are not formed by themselves separately but are
produced upon other trees, as the mistletoe. Plants, however, must
be investigated separately.


Of the generation of animals we must speak as various questions
arise in order in the case of each, and we must connect our account
with what has been said. For, as we said above, the male and female
principles may be put down first and foremost as origins of
generation, the former as containing the efficient cause of
generation, the latter the material of it. The most conclusive proof
of this is drawn from considering how and whence comes the semen;
for there is no doubt that it is out of this that those creatures
are formed which are produced in the ordinary course of Nature; but we
must observe carefully the way in which this semen actually comes into
being from the male and female. For it is just because the semen is
secreted from the two sexes, the secretion taking place in them and
from them, that they are first principles of generation. For by a male
animal we mean that which generates in another, and by a female that
which generates in itself; wherefore men apply these terms to the
macrocosm also, naming Earth mother as being female, but addressing
Heaven and the Sun and other like entities as fathers, as causing

Male and female differ in their essence by each having a separate
ability or faculty, and anatomically by certain parts; essentially the
male is that which is able to generate in another, as said above;
the female is that which is able to generate in itself and out of
which comes into being the offspring previously existing in the
parent. And since they are differentiated by an ability or faculty and
by their function, and since instruments or organs are needed for
all functioning, and since the bodily parts are the instruments or
organs to serve the faculties, it follows that certain parts must
exist for union of parents and production of offspring. And these must
differ from each other, so that consequently the male will differ from
the female. (For even though we speak of the animal as a whole as
male or female, yet really it is not male or female in virtue of the
whole of itself, but only in virtue of a certain faculty and a certain
part- just as with the part used for sight or locomotion- which part
is also plain to sense-perception.)

Now as a matter of fact such parts are in the female the so-called
uterus, in the male the testes and the penis, in all the sanguinea;
for some of them have testes and others the corresponding passages.
There are corresponding differences of male and female in all the
bloodless animals also which have this division into opposite sexes.
But if in the sanguinea it is the parts concerned in copulation that
differ primarily in their forms, we must observe that a small change
in a first principle is often attended by changes in other things
depending on it. This is plain in the case of castrated animals,
for, though only the generative part is disabled, yet pretty well
the whole form of the animal changes in consequence so much that it
seems to be female or not far short of it, and thus it is clear than
an animal is not male or female in virtue of an isolated part or an

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