Of course it’s not that simple. I called it a cornerstone not a whole building but it gives us a starting point and a first approach to a pragmatic semiotic architecture still being built as we speak.
There is more detail and a trace of semiotic’s later development in this paper:
We began by quoting the founding paragraph from Aristotle:
Words spoken are symbols or signs (symbola) of affections or impressions (pathemata) of the soul (psyche); written words are the signs of words spoken. As writing, so also is speech not the same for all races of men. But the mental affections themselves, of which these words are primarily signs (semeia), are the same for the whole of mankind, as are also the objects (pragmata) of which those affections are representations or likenesses, images, copies (homoiomata). (Aristotle, De Interp. i. 16a4).
We used the following Figure to highlight the structure of the triadic relation among objects (pragmata), affections or impressions (pathemata), and symbols or signs (symbola, semeia) as given in Aristotle’s account:
Figure 1. The Sign Relation in Aristotle
The triadic nexus marked “R” in the Figure is what graph theorists call a node or point of degree 3 and it provides a graphical picture of a relational triple that may be taken in any convenient order so long as we keep it constant throughout a given discussion. For example, we could take Aristotle’s object, sign or symbol, and impression in the order mostly just because I find that convenient in later developments.
Diagrams of that sort, whether triangular or tri-radial in form, have long been in common use for conveying the properties of triadic sign relations. But I have discovered to my dismay over the intervening years that people tend to be led astray by pictures like that, often getting stuck on square one, or rather triangle one. That is, they get stuck on single triples of sign relations rather than grasping them as they should, as prototypical examples of a whole class of ordered triples.