*

Next, let us suppose that we find _two Grey_ Counters placed in the
North Half, one in each Cell.

.-------.
|( )|( )|
|---|---|
| | |
.-------.

We know that this represents the Proposition "No x exist".

Similarly we may interpret _two Grey_ Counters, when placed in the
South, or West, or East Half.

* * * * *

Lastly, let us suppose that we find a _Red_ and a _Grey_ Counter placed
in the North Half, the _Red_ in the North-_West_ Cell, and the _Grey_ in
the North-_East_ Cell.

.-------.
|(.)|( )|
|---|---|
| | |
.-------.

We know that this represents the Proposition, "All x are y".

[Note that the _Half_, occupied by the two Counters, settles
what is to be the _Subject_ of the Proposition, and that the
_Cell_, occupied by the _Red_ Counter, settles what is to be its
_Predicate_.]
pg038
Similarly we may interpret a _Red_ and a _Grey_ counter, when placed in
any one of the seven similar positions

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 Sec. =1=, 5-8 (p. 97).]

pg039

BOOK IV.

THE TRILITERAL DIAGRAM.

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