l expression of the
relation we have in view, whether coinherence or causation.

Sec. 3. The sentences of ordinary discourse are, indeed, for the most
part, longer and more complicated than the logical form of propositions;
it is in order to prove them, or to use them in the proof of other
propositions, that they are in Logic reduced as nearly as possible to
such simple but explicit expressions as the above (_tertii adjacentis_).
A Compound Proposition, reducible to two or more simple ones, is said to
be exponible.

The modes of compounding sentences are explained in every grammar-book.
One of the commonest forms is the copulative, such as _Salt is both
savoury and wholesome_, equivalent to two simple propositions: _Salt is
savoury; Salt is wholesome. Pure water is neither sapid nor odorous_,
equivalent to _Water is not sapid; Water is not odorous_. Or, again,
_Tobacco is injurious, but not when used in moderation_, equivalent to
_Much tobacco is injurious; a little is not_.

Another form of Exponible is the Exceptive, as _Kladderadatsch is
published daily, except on week-days_, equivalent to _Kladderadatsch is
published on Sunday; it is not published any other day_. Still another
Exponible is the Exclusive, as _Only men use fire_, equivalent to _Men
are users of fire; No other animals are_. Exceptive and exclusive
sentences are, however, equivalent forms; for we may say,
_Kladderadatsch is published only on Sunday_; and _No animals use fire,
except men_.

There are other compound sentences that are not exponible, since, though
they contain two or more verbal clauses, the construction shows that
these are inseparable. Thus, _If cats are scarce, mice are plentiful_,
contains two verbal clauses; but _if cats are scarce_ is conditional,
not indicative; and _mice are plentiful_ is subject to the condition
that _cats are scarce_. Hence the whole sentence is called a Conditional
Proposition. For the various forms of Conditional Propositions see chap.
v. Sec. 4.

But, in fact, to find the logical force of recognised grammatical forms
is the least of a logician's difficulties in bringing the discourses of
men to a plain issue. Metaphors, epigrams, innuendoes and other figures
of speech present far greater obstacles to a lucid reduction whether for
approval or refutation. No rules can be given for finding everybody's
meaning. The poets have their own way of expressing themselves;
sophists, too, have their own way. And the