The Commens Dictionary
Quote from ‘Logical Tracts. No. 1. On Existential Graphs’
A Graph is a diagram consisting of no more than, first, the sheet upon which it is written, secondly, spots (or their equivalents) having various visible qualities (as colors, etc), third, lines of connection (commonly of only two kinds, those that are drawn and those that are left undrawn), and fourth[,] enclosing ovals.