implies possibility;
in the second it implies liberty; that is, he is at liberty to go or to
stay; in the third, _must_ denotes necessity; _can_ denotes power or
ability; _would_ implies will or inclination; that is, he had a _mind_
to walk; and _should_ implies obligation. Hence you perceive, that the
verbs, may rain, may go, must eat, must drink, can ride, world walk, and
should learn, are in the _potential_ mood.

NOTE 1. As a verb in the indicative mood is converted into the
subjunctive when it is preceded by a conjunction expressing doubt,
contingency, supposition, &c., so a verb in the potential mood, may,
in like manner, be turned into the subjunctive; as, "_If_ I _could
deceive_ him, I should abhor it; _Though_ he _should increase_ in
wealth, he would not be charitable." I _could deceive_, is in the
potential; _If_ I _could deceive_, is in the subjunctive mood.

2. The potential mood, as well as the indicative, is used in asking
a question; as, "May I go? Could you understand him? Must we die?"

The INFINITIVE MOOD expresses action, passion, or being, in a general
and unlimited manner, having no nominative, consequently, neither person
nor number; as, _"To speak, to walk_."

_Infinitive_ means _unconfined_, or _unlimited_. This mood is called the
infinitive, because its verb is not confined or limited to a nominative.
A verb in any other mood is limited; that is, it must agree in number
and person with its nominative; but a verb in this mood has _no_
nominative, therefore, it never changes its termination, except to form
the perfect tense. Now you understand why all verbs are called _finite_
or _limited_, excepting those in the infinitive mood.

NOTE. _To_, the sign of the infinitive mood, is often understood
before the verb; as, "Let me proceed;" that is, Let me _to_ proceed.
See RULE 25. _To_ is not a preposition when joined to a verb in this
mood; thus, _to_ ride, _to_ rule; but it should be parsed with the
verb, and as a part of it.

If you study this lecture attentively, you will perceive, that when I
say, I _write_, the verb is in the indicative mood; but when I say, _if_
I write, or, _unless_ I write, &c. the verb is in the subjunctive mood;
_write_ thou, or _write_ ye or you, the imperative; I _may write_, I
_must write_, I _could write, &c._ the potential; and _to write_, the
infinitive. Any other verb (except the defective) may be employed i