Graphical representations of intersection of sets as logical combinations are much older than Venn.
Euler and Leibniz are often quoted and the current Wikipedia article also quotes Ramon Llull but I do not really find the illustrations provided in the Wiki Commons for Llull very compelling.


I expect that these kind of ideas can be found in many other places and even older times, perhaps in disguise.


In this context I find the heraldic uses of theological diagrams such as shown [here](http://www.absoluteastronomy.com/topics/Shield_of_the_Trinity) quite fascinating as a kind of medieval fashion statement.


Do you know of older examples of graphical representation of logical and/or set relations, for instance of Chinese, Arabic and Greek origin ?


(ps: at least one of the tags is a joke)



What are the oldest illustrations of "Venn" diagrams?
You may already be familiar with Ruskey and Weston's ["A Survey of Venn Diagrams,"](http://www.combinatorics.org/Surveys/ds5/VennEJC.html) which includes a discussion of Borromean rings. Such rings are similar to the valknut and the triskelion, of which the gankyil is a type. All of these figures are quite old.


Of course these observations don't answer your question about the use of graphical representations of logical and/or set relations in antiquity. 


Plato *refers* to diagrams, for example, in his discussion of the double-divided line in Book 6 of *Republic* and in *Meno* when Socrates questions Meno's slave about a problem in geometry -- how to find a square double in area to any given square. I imagine more examples can be found.


An interesting project would be to find examples of "visual" language in the works of Plato, Aristotle, and Euclid.


While writing this post I came across the following two references:


Edwards, Anthony W. F. *Cogwheels of the Mind: The Story of Venn Diagrams.* Baltimore, Maryland: The John Hopkins University Press, (2004). 


Kuehni, Rolf. ["On the Source of d’Aguilon’s Arc Color Mixture Diagram."](http://www4.ncsu.edu/~rgkuehni/unpubAndPresentations.html) Unpublished manuscript, 2003.


