Red in North-East, Grey in North-West; Red in South-West, Grey in South-East; Red in South-East, Grey in South-West; Red in North-West, Grey in South-West; Red in South-West, Grey in North-West; Red in North-East, Grey in South-East; Red in South-East, Grey in North-East. Once more the genial friend must be appealed to, and requested to examine the Reader on Tables II and III, and to make him not only _represent_ Propositions, but also _interpret_ Diagrams when marked with Counters. The Questions and Answers should be like this:-- Q. Represent "No x' are y'." A. Grey Counter in S.E. Cell. Q. Interpret Red Counter on E. partition. A. "Some y' exist." Q. Represent "All y' are x." A. Red in N.E. Cell; Grey in S.E. Q. Interpret Grey Counter in S.W. Cell. A. "No x'y exist" = "No x' are y" = "No y are x'". &c., &c. At first the Examinee will need to have the Board and Counters before him; but he will soon learn to dispense with these, and to answer with his eyes shut or gazing into vacancy. [Work Examples § =1=, 5-8 (p. 97).] pg039 BOOK IV. THE TRILITERAL DIAGRAM. ·-----------------· ·-----------------· | | | | xy | xy' | | | | | m' | m' | | xy | xy' | | ·----|----· | | | | | | xy | xy'| | | | | | | m | m | | |--------|--------| |---|----|----|---| | | | | |x'y |x'y'| | | | | | | m | m | | | x'y | x'y' | | ·----|----· | | | | | x'y | x'y' | | | | | m' | m' | ·-----------------· ·-----------------· CHAPTER I. _SYMBOLS AND CELLS._ First, let us suppose that the above _left_-hand Diagram is the Biliteral Diagram that we have been using in Book III., and that we change it into a _Triliteral_ Diagram by drawing an _Inner Square_, so as to divide each of its 4 Cells into 2 portions, thus making 8 Cells altogether. The _right_-hand Diagram shows the result.