 Category the First is the Idea of that which is such as it is regardless of anything else. That is to say, it is a Quality of Feeling. Category the Second is the Idea of that which is such as it is as being Second to some First, regardless of anything else and in particular regardless of any law, although it may conform to a law. That is to say, it is Reaction as an element of the Phenomenon. Category the Third is the Idea of that which is such as it is as being a Third, or Medium, between a Second and its First. That is to say, it is Representation as an element of the Phenomenon. (EP 2.160) 