se examples, it may be seen,
that Dr. Blair often forgot or disregarded his own doctrine respecting the
use of this relative; though he was oftener led, by the error of that
doctrine, to substitute _which_ for _that_ improperly.

OBS. 36.--_Whether_ was formerly used as an interrogative pronoun, in which
sense it always referred to one of two things; as, "Ye fools and blind! for
_whether_ is greater, the gold, or the temple that sanctifieth the
gold?"--_Matt._, xxiii, 17. This usage is now obsolete; and, in stead of
it, we say, "_Which_ is greater?" But as a disjunctive conjunction,
corresponding to _or_, the word _whether_ is still in good repute; as,
"Resolve _whether_ you will go _or_ not."--_Webster's Dict._ In this sense
of the term, some choose to call _whether_ an _adverb_.

OBS. 37.--In the view of some writers, interrogative pronouns differ from
relatives chiefly in this; that, as the subject referred to is unknown to
the speaker, they do not relate to a _preceding_ noun, but to something
which is to be expressed in the answer to the question. It is certain that
their _person, number_, and _gender_, are not regulated by an antecedent
noun; but by what the speaker supposes or knows of a subject which may, or
may not, agree with them in these respects: as, "_What_ lies there?"
Answer, "Two _men_ asleep." Here _what_, standing for _what thing_, is of
the third person, singular number, and neuter gender; but _men_, which is
the term that answers to it, is of the third person, plural, masculine.
There is therefore no necessary agreement between the question and the
answer, in any of those properties in which a pronoun usually agrees with
its noun. Yet some grammarians will have interrogatives to agree with these
"_subsequents_," as relatives agree with their _antecedents_. The answer,
it must be granted, commonly contains a noun, corresponding in some
respects to the interrogative pronoun, and agreeing with it _in case_; but
this noun cannot be supposed to control the interrogation, nor is it, in
any sense, the word for which the pronoun stands. For every pronoun must
needs stand for something that is uttered or conceived by the same speaker;
nor can any question be answered, until its meaning is understood.
Interrogative pronouns must therefore be explained as direct substitutes
for such other terms as one might use in stead of them. Thus _who_ means
_what person_?

"_Who_ taught that heav'n-directed spire to r