again the differentia of 'animal endowed with feet' must be of it qua endowed with feet. Therefore we must not say, if we are to speak rightly, that of that which is endowed with feet one part has feathers and one is featherless (if we do this we do it through incapacity); we must divide it only into cloven-footed and not cloven; for these are differentiae in the foot; cloven-footedness is a form of footedness.
Beraz, zuzen hitz egitekotan, ez dago esaterik oindunen artean batzuk "hegaldunak" eta besteak "hegalgabeak" direnik (norbaitek hau esaten badu, ezjakintasunagatik izango da), batzuk "behaztunak" eta besteak "behatzgabeak" direla baizik. Hauek oinaren desberdintasunak baitira, 15) behatzak izatea nolabaiteko oinak izatea delako.