species or individuals if they are animals, since each animal is either species or individual.
Likewise, we must observe, whether species or some one of those under species, is predicated of difference, for this is impossible, since difference is more widely predicated than species; further, difference will happen to be species, if a certain species is predicated of it, for if man is predicated (of difference), man is evidently a difference. Again, (see) whether difference be not prior to species, since difference must necessarily be posterior to genus, but prior to species.
Observe, too, whether the assigned difference is of another genus, neither contained by, nor containing it, as the same difference does not appear to be of two genera not comprehending each other. Otherwise, the same species would happen to be in two genera not comprehending each other, since each difference introduces its own appropriate genus, as pedestrian and biped co-introduce animal; wherefore, if each of the genera be predicated of what the difference is, it is evident that the species is in two genera not comprehending each other. Or is it not impossible that there should be the same difference of two genera not comprehending each other, but it must be added, neither are both under the same? For pedestrian animal, and winged animal, are genera not comprehending each other, and biped is a difference of both these, wherefore, it must be added, that neither are both under the same, for both of these are under animal. It is evident, also, that difference need not always introduce its appropriate genus, since there may be possibly the same (difference) of two genera not comprehending each other, but it is necessary that it should co-introduce one alone, and those which are above it, as biped, winged, pedestrian, co-introduce animal.
Observe, also, whether to be in a certain thing is assigned as the difference of substance, for substance does not seem to differ from substance in being some where, wherefore also, those are to be blamed, who divide animal by pedestrian and aquatic, as if pedestrian and aquatic signified being some where. Or are they
