C. S. Peirce Manuscripts

πλ 2

with the country, no man of it would ever be of the slightest use to you in laying out your detailed plans? To that he must have rejoined, "I do not say that because I might wish to stick in pins in order to trace out and study the daily changes of the situations." To that, again, my surrejoinder should have been, "Well, General, that precisely corresponds to the advantage of a diagram of the course of thought. Indeed, just there is the advantage of diagrams in general. Namely, one can make exact experiments upon diagrams, and look out for unintended change thereby brought about in the relations of different parts of the diagram to one another. These operations in reasoning take the place of the experiments upon real things that one performs in chemical and physical research. Chemists have sometimes described