proposition, then, may first be described in the language of grammar as
_a sentence indicative_; and it is usually expressed in the present
tense.

It is true that other kinds of sentences, optative, imperative,
interrogative, exclamatory, if they express or imply an assertion, are
not beyond the view of Logic; but before treating such sentences, Logic,
for greater precision, reduces them to their equivalent sentences
indicative. Thus, _I wish it were summer_ may be understood to mean,
_The coming of summer is an object of my desire_. _Thou shalt not kill_
may be interpreted as _Murderers are in danger of the judgment_.
Interrogatories, when used in argument, if their form is affirmative,
have negative force, and affirmative force if their form is negative.
Thus, _Do hypocrites love virtue?_ anticipates the answer, _No_. _Are
not traitors the vilest of mankind?_ anticipates the answer, _Yes_. So
that the logical form of these sentences is, _Hypocrites are not lovers
of virtue_; _Traitors are the vilest of mankind_. Impersonal
propositions, such as _It rains_, are easily rendered into logical forms
of equivalent meaning, thus: _Rain is falling_; or (if that be
tautology), _The clouds are raining_. Exclamations may seem capricious,
but are often part of the argument. _Shade of Chatham!_ usually means
_Chatham, being aware of our present foreign policy, is much
disgusted_. It is in fact, an appeal to authority, without the
inconvenience of stating what exactly it is that the authority declares.

§ 2. But even sentences indicative may not be expressed in the way most
convenient to logicians. _Salt dissolves in water_ is a plain enough
statement; but the logician prefers to have it thus: _Salt is soluble in
water_. For he says that a proposition is analysable into three
elements: (1) a Subject (as _Salt_) about which something is asserted or