Those among the Aristotelian commentators who denied the title of _Ad Aliquid_ to a place among the Categories or _Summa Genera_ of predicates, might support their views from passages where Aristotle ranks the Genus as a _Relatum_, though he at the same time declares that the Species under it are not _Relata_. Thus _scientia_ is declared by him to be a _Relatum_; because it must be _of something--alicujus scibilis_; while the _something_ thus implied is not specified.[95] But (_scientia_) _musica_, _grammatica_, _medica_, &c., are declared not to be _Relata_; the indeterminate _something_ being there determined, and bound up in one word with the predication of Relativity. Now the truth is that both are alike _Relata_, though both also belong to the Category of Quality; a man is called _Talis_ from being _sciens_, as well as from being _grammaticus_. Again, he gives as illustrative examples of the Category _Ad Aliquid_, the adjectives double, triple. But he ranks in a different Category (that of _Quantum_) the adjectives bicubital, tricubital ([Greek: dipê=chus, tripê=chus]. It is plain that the two last of these predicates are species under the two first, and that all four predicates are alike relative, under any real definition that can be given of Relativity, though all four belong also to the Category of _Quantum_. Yet Aristotle does not recognize any predicates as belonging to _Ad Aliquid_, except such as are logically and grammatically elliptical; that is, such as do not include in themselves the specification of the Correlate, but require to be supplemented by an additional word in the genitive or dative case, specifying the latter. As we have already seen, he lays it down generally, that all _Relata_ (or _Ad Aliquid_) imply a _Correlatum_; and he prescribes that when the _Correlatum_ is indicated, care shall be taken to designate it by a precise and specific term, not of wider import than the _Relatum_,[96] but specially reciprocating therewith: thus he regards _ala_ (a wing) as _Ad Aliquid_, but when you specify its correlate in order to speak with propriety ([Greek: oi)kei/ôs]), you must describe it as _ala alati_ (not as _ala avis_), in order that the _Correlatum_ may be strictly co-extensive and reciprocating with the _Relatum_. Wing, head, hand, &c., are thus _Ad Aliquid_, though there may be no received word in the language to express their exact _Correlata_; and though you may find it necessary to coin a new word expressly for the purpose.[97] In specifying the _Correlatum_ of servant, you must say, servant _of a master_, not servant of a man or of a biped; both of which are in this case accompaniments or accidents of the master, being still accidents, though they may be in fact constantly conjoined. Unless you say master, the terms will not reciprocate; take away master, the servant is no longer to be found, though the man who was called _servant_ is still there; but take away