…when I speak of a graph, I mean the general type of whatever means the same thing and expresses that meaning in the same way, so far as the conventions of this system take cognizance of the ways; while that which is scribed once and only once and embodies the graph, I call a graph-replica.
A sign on the sheet of assertion or on any other area, made by a single action or series of acts of scribing and expressive, according to the conventions of this system [of existential graphs], of an intelligible state of things, shall be called a graph-replica.
It is necessary to recognize the facile distinction between a graph and a graph-instance. A graph-instance is a token, that is, is an existent individual object, which signifies a proposition. It can never be duplicated. Attempt to duplicate it, and the duplicate will be a graph-instance of the same signification in all respects, but it will not be that individual graph-instance of which it is the precise copy. I scribe, that is, write or draw, a sign meaning Tully was Cicero. I duplicate it precisely. The new sign will be substantially the same. It will only differ so much as is necessary to make it a second scribing of precisely the same type. But it will not be the same graph-instance. A graph, on the other hand, is a type.