the reply is that if animality and rationality are accidents, they are attributes of the human being. If they are substances, [one substance] is sentient and another substance grows; the invalidity of this is well known.

The truth is that these are attributes both of what is conceived in the mind and of what exists externally, and that the essence has a greater claim to constituting its attributes than the attributes have to constituting the essence.

Furthermore, if they intend a detailed conception of the attributes, it is clear that their expression “rational animal” does not yield a detailed conception of all the essential attributes. Being a body that grows, senses, and moves voluntarily is conveyed by the term “animal” only in summary, not in detail. If, however, they mean conception in general, whether summary or detailed, then clearly the term “human being” signifies both animality and rationality, just as the term “animal” signifies a body that grows, senses, and moves voluntarily. Thus, the term “human being” suffices to make known the attributes of a human being, just as the term “animal” suffices to make known the attributes of an animal.

If, then, in defining the human being they offer only an expression that signifies its essential attributes in summary, and the term “human being” already conveys this much, their definition is of the same kind as definition by names, and what they classify as a definition is of the same kind as what they classify as a name.