§1. Original Statement
555. The five conceptions thus obtained, for reasons which will be sufficiently obvious, may be termed categories. That is,
Quality (reference to a ground)
Relation (reference to a correlate)
Representation (reference to an interpretant)
The three intermediate conceptions may be termed accidents.
556. This passage from the many to the one is numerical. The conception of a third is that of an object which is so related to two others, that one of these must be related to the other in the same way in which the third is related to that other. Now this coincides with the conception of an interpretant. An other is plainly equivalent to a correlate. The conception of second differs from that of other, in implying the possibility of a third. In the same way, the conception of self implies the possibility of an other. The ground is the self abstracted from the concreteness which implies the possibility of another.
557. Since no one of the categories can be prescinded from those above it, the list of supposable objects which they afford is,
Quale (that which refers to a ground)
Relate (that which refers to ground and correlate)
Representamen (that which refers to ground, correlate, and interpretant)
558. A quality may have a special determination which prevents its being prescinded from reference to a correlate. Hence there are two kinds of relation.
First. That of relates whose reference to a ground is a prescindible or internal quality.
Second. That of relates whose reference to a ground is an unprescindible or relative quality.
In the former case, the relation is a mere concurrence of the correlates in one character, and the relate and correlate are not distinguished. In the latter case the correlate is set over against the relate, and there is in some sense an opposition.
Relates of the first kind are brought into relation simply by their agreement. But mere disagreement (unrecognized) does not constitute relation, and therefore relates of the second kind are only brought into relation by correspondence in fact.
A reference to a ground may also be such that it cannot be prescinded from a reference to an interpretant. In this case it may be termed an imputed quality. If the reference of a relate to its ground can be prescinded from reference to an interpretant, its relation to its correlate is a mere concurrence or community in the possession of a quality, and therefore the reference to a correlate can be prescinded from reference to an interpretant. It follows that there are three kinds of representations.
First. Those whose relation to their objects is a mere community in some quality, and these representations may be termed likenesses.1)
Second. Those whose relation to their objects consists in a correspondence in fact, and these may be termed indices or signs.2)
Third. Those the ground of whose relation to their objects is an imputed character, which are the same as general signs, and these may be termed symbols.