ics are not
properly selected, the definition though logical in form may be inexact,
because the differentia do not exclude all but the term to be defined. If
we say, "Exposition is that form of discourse which gives information,"
the definition is inexact because there are other forms of discourse that
give information. Many definitions given in text-books are inexact. Care
should be taken to distinguish them from those which are logically exact.

EXERCISE

Which of the following are exact?

1. A sheep is a gregarious animal that produces wool.

2. A squash is a garden plant much liked by striped bugs.

3. A pronoun is a word used for a noun.

4. The diaphragm is a sheet of muscle and tendon, convex on its upper
side, and attached by bands of striped muscle to the lower ribs at the
side, to the sternum, and to the cartilage of the ribs which join it in
front, and at the back by very strong bands to the lumbar vertebrae.

5. A man is a two-legged animal without feathers.

6. Argument is that form of discourse which has for its object the proof
of the truth or falsity of a proposition.

7. The base of an isosceles triangle is that side which is equal to no
other.

8. Zinc is a metal used under stoves.

9. The epidermis of a leaf is a delicate, transparent skin which covers
the whole leaf.

+Theme LXXXVIII.+--_Write an expository paragraph about one of the
following:_--

Suggested subjects:--
1. Household science and arts.
2. Architecture.
3. Aesthetics.
4. Poetry.
5. Fiction.
6. Half tones.
7. Steam fitting.
8. Swimming.

(Consider the definitions you have used.)

+162. Division.+--The second step in the exposition of a term is division.
Definition establishes the limits of the term. Division separates into its
parts that which is included by the term. By definition we distinguish
triangles from squares, circles, and other plane figures. By division we
may separate them into scalene, isosceles, and equilateral, or if we
divide them according to a different principle into right and oblique
triangles. In either case the division is complete and exact. By
completeness is meant that every object denoted by the term explained is
included in the division given, thus making the sum of these divisions
equal to the whole. By exactness is meant that but a single principle has
been used, and so no object denoted by the term explained will be included
in more than one of the divisio