When Aristotle says, very truly, that if the First Substances were non-existent, none of the other Predicaments could exist, we must understand what he means by the term _first_. That term bears, in this treatise, a sense different from what it bears elsewhere: here it means the extreme concrete and individual; elsewhere it means the extreme abstract and universal. The First Substance or First Essence, in the Categories, is a _Hoc Aliquid_ ([Greek: to/de ti]), illustrated by the examples _hic homo_, _hic equus_. Now, as thus explained and illustrated, it includes not merely the Second Substance, but various accidental attributes besides. When we talk of This man, Sokrates, Kallias, &c., the hearer conceives not only the attributes for which he is called a man, but also various accidental attributes, ranking under one or more of the other Predicaments. The First Substance thus (as explained by Aristotle) is not conceived as a mere _substratum_ without Second Substance and without any Accidents, but as already including both of them, though as yet indeterminately; it waits for specializing words, to determine what its Substance or Essence is, and what its accompanying Accidents are. Being an individual (_Unum numero_), it unites in itself both the essential attributes of its species, and the unessential attributes peculiar to itself.[115] It is already understood as including attributes of both kinds; but we wait for predicates to declare ([Greek: dêlou=n--a)podido/nai][116]) what these attributes are. The First or Complete _Ens_ embodies in itself all the Predicaments, though as yet potential and indeterminate, until the predicating adjuncts are specified. There is no priority, in the order of existence, belonging to Substance over Relation or Quality; take away either one of the three, and the First _Ens_ disappears. But in regard to the order of exposition, there is a natural priority, founded on convenience and facility of understanding. The _Hoc Aliquid_ or _Unum Numero_, which intimates in general outline a certain concretion or co-existence of attributes, though we do not yet know what they are--being as it were a skeleton--comes naturally as Subject before the predicates, whose function is declaratory and specifying as to those attributes: moreover, the essential attributes, which are declared and connoted when we first bestow a specific name on the subject, come naturally before the unessential attributes, which are predicated of the subject already called by a specific name connoting other attributes.[117] The essential characters are native and at home; the accidental attributes are domiciliated foreigners.[118]