In this relation, our grammar is a text-book, which we take as a guide, or use as a help to our own observation.

_Fifthly_, It is as a single voyage, to the open sea, the highway of nations.

Such is our meaning, when we speak of the grammar of a particular text or passage.
4.

Again: Grammar is to language a sort of self-examination.

It turns the faculty of speech or writing upon itself for its own elucidation; and makes the tongue or the pen explain the uses and abuses to which both are liable, as well as the nature and excellency of that power, of which, these are the two grand instruments.