The question might be raised as to why woman does not differ in species from man, seeing that female is contrary to male, and difference is contrariety; and why a female and a male animal are not other in species, although this difference belongs to animal
per se, and not as whiteness or blackness does; male
and female
belong to it qua animal.
This problem is practically the same as why does one kind of contrariety (e.g.
The answer may be that in the one case the attributes are peculiar to the genus, and in the other they are less so; and since one element is formula and the other matter, contrarieties in the formula produce difference in species, but contrarieties in the concrete whole do not.footed
and winged
) make things other in species, while another (e.g. whiteness and blackness) does not?
Hence the whiteness or blackness of a man does not produce this, nor is there any specific difference between a white man and a black man; not even if one term is assigned to each. For we are now regarding man
as matter, and matter does not produce difference; and for this reason, too, individual men are not species of man,
although the flesh and bones of which this and that man consist are different. The concrete whole is other,
but not other in species,
because there is no contrariety in the formula, and this is the ultimate indivisible species.
But Callias is definition and matter. Then so too is white man,
because it is the individual, Callias, who is white. Hence man
is only white accidentally. Again, a bronze circle and a wooden one do not differ in species; and a bronze triangle and a wooden circle differ in species not because of their matter, but because there is contrariety in their formulae.
But does not matter, when it is other
in a particular way, make things other in species
? Probably there is a sense in which it does. Otherwise why is this particular horse other in species
than this particular man, although the definitions involve matter? Surely it is because there is contrariety in the definition, for so there also is in white man
and black horse
; and it is a contrariety in species, but not because one is white and the other black; for even if they had both been white, they would still be other in species.
Male
and female
are attributes peculiar to the animal, but not in virtue of its substance; they ar material or physical. Hence the same semen may, as the result of some modification, become either female or male.
We have now stated what to be other in species
means, and why some things differ in species and others do not.