Alex, Doug F, 

I'm attaching a PDF of the article I sent yesterday.   This version has diagrams that will clarify many of the issues.

Figure 2 is fundamental, and Figures 3 and 4 clarify some of the details.  (To Alex :  every diagram is a structure, and every structure is a diagram.  They serve exactly the same purpose.)

Doug F> Even if most everybody often thinks in diagrams, that doesn't mean it is
the sole method of thinking.  If i am listening to a bird or insect making
noises outside my window, my attempt to recognize the type of animal is
not diagramatic.  If i am smelling a flower blindfolded, my attempt to
recognize the type of bloom is not diagramatic.  If i am petting my cat
while reading and detect a bur in her fur, that is not diagramatic.

[JFS> All those sensations and actions are continuous.  But  if you want to talk about them or relate them to your inner stock of discrete words/concepts, you must simplify them to a structure/diagram that is constructed of discrete parts.]

DF>  If I taste something i am cooking to determine whether to add more (and which)
herb or spice, i am not engaged in diagrammatic thinking. 

[JFS> Now you have converted the continuous perceptions to discrete units (concepts/words).   That can be represented as a structure or diagram.  A sentence made up of words is just a one-dimensional diagram/structure.  A moving multidimensional diagram can be a much closer map to your perceptions, plans, and actions.  That is what Peirce called diagrammatic thinking.]

In every one of those examples, the percept is a continuous reflection of external imagery.   As Figures 2, 3, and 4show, that continuous information must be mapped to discrete units before they can be mapped to and from any language that has discrete words or concepts.

Peirce used the word 'diagram', and Alex used the word 'structure', you could also use words like graph, hypergraph, or whatever.   But the critical issue is that some discrete structure of some kind must serve as the intermediate stage between a continuous world and any discrete set of words or concepts used to talk about it.  I also attached a long list of references, which represent a small subset of the things I have consulted while developing the ideas in that article.   I invite you to explore them (and/or any others you may prefer).

John