1. _Who_ should never be applied to animals. The following
application of it is erroneous:--"He is like a _least_ of prey,
_who_ destroys without pity." It should be, _that_ destroys, &c.
2. _Who_ should not be applied to children. It is incorrect to say,
"The _child whom_ we have just seen," &c. It should be, "The child
_that_ we have just seen."
3. _Which_ may be applied to persons when we wish to distinguish one
person of two, or a particular person among a number of others; as,
"_Which_ of the two? _Which_ of them is he?"
4. _That_, in preference to _who_ or _which_, is applied to persons
when they are qualified by an adjective in the superlative degree,
or by the pronominal adjective _same_; as, "Charles XII., king of
Sweden, was one of the _greatest_ madmen _that_ the world ever
saw;--He is the _same_ man _that_ we saw before."
5. _That_ is employed after the interrogative _who_, in cases like
the following; "Who _that_ has any sense of religion, would have
argued thus?"
When the word _ever_ or _soever_ is annexed to a relative pronoun, the
combination is called a _compound pronoun_; as, _whoever_ or _whosoever,
whichever_ or _whichsoever, whatever_ or _whatsoever_.