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Right III.
Two encolsures one within the other with nothing between can anywhere be erased or inserted.

Right IV.
Under an enclosure containing a pseudograph,it makes no difference what else is written, and the enclosure with all it encloss may be erased.

By using these rights we can draw from any premisses any inferences that they justify and not merely the stupid syllogiams of the logic-books.
I will now proceed to prove to you that we have these rights, and you will thereby gain a new light on the interpretation of graphs.
The proof is excessively simple; but of course it is necessary to pay attention in order to follow it.

Of course, we have at any moment a right to clean everything on the the blackboaard by a general erasure; for that is merely to cease insisting on our