he x-Class into the two Classes whose
Differentiae are "y" and "y'", and that we have assigned the North-_West_
Cell to the one (which we may call "the xy-Class"), and the North-_East_
Cell to the other (which we may call "the xy'-Class").

[For example, we might say "Let y mean 'English,' so that y'
will mean 'foreign'", and we might suppose that we had
subdivided "old books" into the two Classes whose Differentiae
are "English" and "foreign", and had assigned the North-_West_
Cell to "old _English_ books", and the North-_East_ Cell to "old
_foreign_ books."]

Fourthly, let us suppose that we have subdivided the x'-Class in the
same manner, and have assigned the South-_West_ Cell to the x'y-Class,
and the South-_East_ Cell to the x'y'-Class.

[For example, we might suppose that we had subdivided "new
books" into the two Classes "new _English_ books" and "new
_foreign_ books", and had assigned the South-_West_ Cell to the
one, and the South-_East_ Cell to the other.]

It is evident that, if we had begun by dividing for y and y', and had
then subdivided for x and x', we should have got the _same_ four
Classes. Hence we see that we have assigned the _West_ Half to the
y-Class, and the _East_ Half to the y'-Class.
pg024
[Thus, in the above Example, we should find that we had assigned
the _West_ Half of the table to "_English_ books" and the _East_
Half to "_foreign_ books."

.-------------------.
| old | old |
| English | foreign |
| books | books |
|---------|---------|
| new | new |
| English | foreign |
| books | books |
.-------------------.

We have, in fact, assigned the four Quarters of the table to
four different Classes of books, as here shown.]

The Reader should carefully remember that, in such a phrase as "the
x-Things," the word "Things" means that particular _kind_ of Things, to
which the whole Diagram has been assigned.

[Thus, if we say "Let Univ. be 'books'," we mean that we have
assigned the whole Diagram to "books." In that case, if we took
"x" to mean "old", the phrase "the x-Things" would mean "the old
books."]

The Reader should not go on to the next Chapter until he is _quite
familiar_ with the _blank_ Diagram I have advised him to draw.

He ought