Man’s distinctive characteristic is his type of consciousness—a consciousness
able to abstract, to form concepts, to apprehend reality by a process of reason
. . . [The] valid definition of man, within the context of his knowledge and of
all of mankind’s knowledge to-date [is]: “A rational animal.”
(“Rational,” in this context, does not mean “acting invariably in accordance
with reason”; it means “possessing the faculty of reason.” A full biological
definition of man would include many subcategories of “animal,” but the general
category and the ultimate definition remain the same.)