e "with propriety."

_That_, in the sentence before us, is an adjective, referring to the
following sentence, which is the _object_ of _wrote_, or is the thing
written. "He wrote to me _that_" fact, sentiment, opinion,
determination, or resolution, that writing, letter, or word--"he will
adopt the new system of grammar, if he can procure some books."

This subject properly belongs to that department of language called
syntax; but as I shall not be able to treat of that in this course of
lectures, I throw in here these brief remarks to give you some general
ideas of the arrangement of words into sentences, according to their
true meaning, as obtained from a knowledge of their etymology. You
cannot fail to observe this method of constructing language if you will
pay a little attention to it when reading; keeping all the time in view
the fact that words are only the signs of ideas, derived from an
observation of things. You all know that it is not merely the steam that
propels the boat, but that it is steam _applied to machinery_. Steam is
the more latent cause; and the engine with its complicated parts is the
direct means. In the absence of either, the boat would not be propelled.
In the formation of language, I may say correctly, "Solomon _built_ the
temple;" for he stood in that relation to the matter which supposes it
would not have been built without his direction and command. To
accomplish such an action, however, he need not raise a hammer or a
gavel, or draw a line on the trestle board. His command made known to
his ministers was sufficient to _cause_ the work to be done. Hence the
whole fact is _indicated_ or declared by the single expression, "Solomon
_built_ the temple."

The Imperative mood is unchanged in form. I can say to one man, _go_, or
to a thousand, _go_. The commander when drilling _one_ soldier, says,
_march_; and he bids the whole battalion, _march_. The agent who is _to
perform_ the action is understood when not expressed; as, _go_, _go
thou_, or _go you_. The agent is generally omitted, because the address
is given direct to the person who is expected to obey the instruction,
request, or command. This verb always agrees with an agent in the
_second_ person. And yet our "grammars made easy" have given us _three
persons_ in this mood--"_Let me love_; _love_, _love thou_, or _do_ thou
_love_; let him love." In the name of common sense, I ask, what can
children learn by such instruction? "_Let me lov