The Commens Dictionary

Quote from ‘Logical Tracts. No. 2. On Existential Graphs, Euler's Diagrams, and Logical Algebra’

A certain sheet, called the sheet of assertion, is appropriated to the drawing upon it of such graphs that whatever may be at any time drawn upon it, called the entire graph, shall be regarded as expressing an assertion by an imaginary person, called the graphist, concerning a universe, perfectly definite and entirely determinate, but the arbitrary creation of an imaginary mind, called the grapheus.